Review of agricultural practices and how they relate to...

Review of agricultural practices for integrated farm management

and how they relate to government sustainability policy objectives

Prepared as part of Defra project IF0124

Jon Moorby1

Huw Powell1

Jason Gittins2

David Moorhouse2

Heleen van de Weerd2

1 Institute of Biological, Environmental and Rural Sciences, Gogerddan, Aberystwyth, SY23 3EB

2 ADAS UK Ltd – Drayton, Alcester Road, Stratford-upon-Avon, Warwickshire CV37

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IF0124 Livestock IFM review, page 2

Table of Contents 1. Summary ............................................................................................................. 5 2. Introduction ......................................................................................................... 6 3. Animal Health ...................................................................................................... 8

3.1. High standards of biosecurity ........................................................................ 8 3.2. High health status, low mortality .................................................................... 9 3.3. Use of prophylactics (vaccines, dips etc.) and medications .......................... 9 3.4. Active use of farm health plans ................................................................... 10 3.5. Prompt use of veterinary services ............................................................... 11 3.6. Routine use of other health services (e.g. foot trimmers) ............................ 11 3.7. Carcass disposal via approved on-site incinerator ...................................... 12 3.8. Carcass disposal via approved off-site methods ......................................... 13 3.9. Use of biological controls for pests and parasites ....................................... 14

4. Animal Nutrition ................................................................................................. 16 4.1. Use of home-grown protein crops ............................................................... 16 4.2. Feed mixed on site ...................................................................................... 18 4.3. Raw feed materials sourced on 'least cost' basis ........................................ 19 4.4. Use of own-grown crops in compound feed ................................................ 19 4.5. All feed purchased from compounder ......................................................... 19 4.6. Use of higher quality feeds for better efficiency ........................................... 20 4.7. Use of permitted co-products ...................................................................... 20 4.8. Use of phase feeding .................................................................................. 21 4.9. Use of low crude protein diets ..................................................................... 22 4.10. Use of enzymes, digestive enhancers and chemicals in feed .................. 24 4.11. Use of feed systems that minimise physical wastage .............................. 25 4.12. Use of drinking systems that minimise water wastage ............................. 26 4.13. Use of own local water supply ................................................................. 26 4.14. Use of mains water supply ....................................................................... 27

5. Nutrient Management ........................................................................................ 29 5.1. Reduce fertiliser use ................................................................................... 29 5.2. On-site solid manure storage in a farm midden ........................................... 30 5.3. Field storage of manure prior to spreading ................................................. 31 5.4. Frequent removal of manure from house .................................................... 32 5.5. Use of manure on site of production as part of 'whole farm' approach ........ 33 5.6. Active nutrient management planning ......................................................... 34 5.7. Spread manures to land in compliance with a Manure Management Plan .. 36


5.8. Time manure / slurry applications to land to maximise fertiliser value and minimise pollution ................................................................................................. 36 5.9. Methods of manure application to land: broadcast on land, no incorporation 37 5.10. Methods of manure application to land: rapid incorporation ..................... 37 5.11. Use of mechanical separation of manures and slurries ........................... 38 5.12. Capture of dirty water in covered stores .................................................. 39 5.13. Capture of dirty water in un-covered stores ............................................. 39 5.14. Use of covered slurry stores .................................................................... 40 5.15. Integral store and cover (bag) .................................................................. 41 5.16. Use of aerators for slurry systems ........................................................... 41 5.17. Use of nitrification inhibitors ..................................................................... 42 5.18. Use of urease inhibitors ........................................................................... 43 5.19. Account taken of land/receptor/weather considerations regarding application practices ............................................................................................. 43 5.20. Account taken of cross compliance, including local restrictions e.g. NVZ 43 5.21. Use of anaerobic digesters for manure .................................................... 45

6. Housing and Environmental Control .................................................................. 46 6.1. Bedding type ............................................................................................... 46 6.2. Mobile versus static housing for outdoor access systems ........................... 49 6.3. Use of stand-off pads .................................................................................. 50 6.4. Use of lower stocking density systems ........................................................ 50 6.5. Use of existing and 'traditional' farm buildings for multiple uses .................. 51 6.6. Environment controlled to optimise production ............................................ 52 6.7. Use of natural ventilation systems ............................................................... 53 6.8. Use of powered ventilation systems ............................................................ 54 6.9. Ventilation requirements efficiently delivered - optimum fan performance .. 55 6.10. Use of renewable energy sources ........................................................... 55 6.11. Use of heat recovery systems .................................................................. 57 6.12. Use of sprinkling or misting systems ........................................................ 57 6.13. Use of energy-efficient or natural light sources ........................................ 58 6.14. Use of light dimmers and timers to save power ....................................... 59 6.15. Use of systems that allow animals free choice ........................................ 59 6.16. Use only of dry-clean methods for house cleaning .................................. 60 6.17. Use of recycled water for house cleaning ................................................ 61 6.18. Optimal use of chemicals during clean-out .............................................. 61 6.19. Use of detergents/degreasers at clean-out .............................................. 61

7. Land and Soil Management .............................................................................. 63


7.1. Ensure suitability of land for outdoor livestock production ........................... 63 7.2. Use of paddock rotation .............................................................................. 64 7.3. Use of field rotation - crops/animals ............................................................ 67 7.4. Outdoor areas shared with other livestock .................................................. 68 7.5. Maintain grass pastures at optimum heights, excess grass cut and utilised 70 7.6. Establish areas of vegetation on site, for conservation purposes ................ 70 7.7. Construct wetlands, swales for water treatment .......................................... 71 7.8. Use of multiple field entrances .................................................................... 71 7.9. Use of movable drinking water troughs ....................................................... 72 7.10. Use of cow tracks ..................................................................................... 72 7.11. Use of buffer strips/zones ........................................................................ 73

8. Enterprise Type ................................................................................................. 75 8.1. Small unit size - below IPPC threshold ....................................................... 75 8.2. Large unit size - above IPPC threshold ....................................................... 76 8.3. Use of traditional breeds (less productive, slower growing etc.) .................. 76 8.4. Use of carefully-bred, productive breeds ..................................................... 78 8.5. All stock home bred or home reared ........................................................... 80 8.6. Switch to all-in, all-out batch production ...................................................... 80 8.7. Reliance on artificial insemination ............................................................... 81 8.8. Extended cycle length, less frequent stock movement ................................ 81 8.9. End weight: High, Medium, or Low .............................................................. 82 8.10. Extended grazing of dairy cattle ............................................................... 83 8.11. Increased stocking density ....................................................................... 85 8.12. Outdoor pig rearing .................................................................................. 87 8.13. Upland beef and sheep finishing .............................................................. 88

9. References ........................................................................................................ 90


1. Summary

Integrated farm management (IFM) takes a whole-farm approach to farming, ensuring that the overall management of farm operations combine and synergise to make farming a successful and sustainable business. Few farm operations can be carried out in isolation of other activities, although IFM is sometimes viewed as farming in an environmentally sustainable way, farming activities have a significant effect on wider policy considerations such as food production, water use and gaseous pollutant outputs. Integrating farm management to make the most efficient use of available resources (livestock, nutrients, and people) also improves the financial profitability of the farm business, without which a farmer is unable to operate. This review considers key practices carried out on livestock farms in relation to a range of important government policy objectives. These objectives fall into the broad headings of Energy, Climate Change and Pollution, Water, Waste, Food and Farming, and Resource Protection. Although farm businesses can vary considerably, from highly intensive indoor pig and poultry production to high extensive upland sheep production, a number of principles can broadly apply across most farm types. Healthy and productive livestock is of paramount importance, coupled with the animals’ appropriate nutrition and environmental care (housing). These two factors influence the production, composition and management of excreta and other nutrients that provide a valuable resource, but also a significant source of pollution. Therefore, farm practices were divided into the major headings of Animal Health, Animal Nutrition, Nutrient Management, Housing and Environmental Control, Land and Soil Management, and Enterprise Type. No single factor or practice can be identified as making the biggest contribution to meeting specific government policy objectives. This, however, highlights the importance of IFM to ensure that all practices carried out on a farm are examined and are taken into consideration as part of the overall farm operation.


2. Introduction

Farms produce food. The systems used to do this involve numerous interacting factors that cannot be considered in isolation. The driving factor for the farmer is the need to make a profit, although an array of other factors including enterprise type, location, legal and voluntary regulations, and the farmer’s personal interests, all contribute to the manner in which the farm operates. Farming practices may be aimed at food production, but because few of these practices happen in isolation many of them have secondary effects on each other and on the wider farm environment. Some of these practices relate to resource use, while others relate to secondary outputs or emissions of potentially polluting products, which can in turn affect other land users such as neighbouring communities and local wildlife. For sustainable livestock agriculture, economic, social and environmental parameters must be considered. A range of government policies operate to encourage best practice using a combination of voluntary schemes and legislation. Policy objectives identified by the Defra policy team, falling under the general areas of energy, climate change and pollution, water, waste, food and farming, and resource protection are listed in Table 2.1. The objective of this study was to review a range of key farming practices and relate them to these policy objectives with specific reference to livestock farms. Farming practices were divided into six major categories: animal health, animal nutrition, nutrient management, housing and environmental control, land and soil management, and enterprise type. Within these categories major farming practices that relate to livestock enterprises were considered, with specific reference to dairy and beef cattle, sheep, pigs, and growing and laying poultry. Each practice was reviewed using robust information obtained from the peer-reviewed literature and from recent and on-going research projects. Interactions with other farming practices were also considered, because best practice to meet one policy objective is not necessarily best practice to meet another.


Table 2.1. List of policy objectives identified by the Defra policy team relating to the requirements of UK farming. Area Policy Objective Energy Reduce farm energy consumption Increase farm energy efficiency Increase use of on-farm renewable energy Climate Change Reduce point source ammonia emissions & Pollution Reduce GHG emissions (carbon dioxide, methane, nitrogen oxides) Reduce dust emissions Reduce farm odour & nuisance Water Increase efficiency of water use Maintain / improve water quality Reduce risks of water contamination incidents Reduce flooding and / or erosion Waste Reduce waste and CO2 emissions from inputs Reduce waste and CO2 emissions from outputs Increase efficiency of use of resources Increase recycling/composting, reduce landfill Increase use of recycled materials Food and Consistent with all other legal requirements Farming Improve standard of animal welfare Improve animal health status Protect against animal disease impact Improve on-farm environmental benefit Increase acceptability to customers Improve livestock output or performance Provides rural employment Ensures food availability to meet consumer demand Provides safe, good quality food Resource Encourages integrated farming methods protection Reduced use of chemicals Inclusion in agri-environment scheme Sustainable management of land Improve soil management and fertility Enhances or safeguards on-farm biodiversity Improve leisure access to natural environment Improve cleanliness of local environment Maintain and improve living landscape


3. Animal Health

List of practices considered most important in the area of animal health and considered in this section. 3.1 High standards of biosecurity 3.2 High health status, low mortality 3.3 Use of prophylactics (vaccines, dips etc.) and medications 3.4 Active use of farm health plans 3.5 Prompt use of veterinary services 3.6 Routine use of other health services (e.g. foot trimmers) 3.7 Carcass disposal via approved on-site incinerator 3.8 Carcass disposal via approved off-site methods 3.9 Use of biological controls for pests and parasites 3.1. High standards of biosecurity Biosecurity is of prime importance for livestock producers. There is high industry awareness of the issue, particularly following the outbreaks of Foot and Mouth Disease in 2001, which resulted in the Disease Control (England) Order 2003 (Statutory Instrument 2003 No. 1729), which implements the 6 day standstill rule for cattle, sheep and goats, and the 20 day standstill rule for swine. Biosecurity has also become a major issue in the poultry sector, particularly following the concerns over avian influenza.

Efficiency of water use Possibly more water is used for clean-out especially for batch production systems but there is scope for targeted approaches.

Animal health status High standards of biosecurity help to maintain high animal health status. High animal health status leads to high quality food for humans, and it is important to help prevent zoonoses (e.g. toxoplasmosis; Kijlstra et al., 2004)

Protection against animal disease impact High levels of biosecurity reduce the risk of disease outbreak within a herd or flock. This is consistent with higher health status, improved animal welfare and lower cost sustainable levels of production. Effect on livestock output or performance There is a positive effect through enhanced health and performance. On-farm use of chemicals Possibly more chemicals are used but there is scope for targeted approaches. Leisure access to the natural environment A single point of entry to the farm, which allows for disinfection of machinery and personnel, is preferable but not always possible if public rights of way exist across the farm. The use of perimeter fence, with double strands of electric fencing, or


double fencing to prevent physical contact with animals on neighbouring farms, reduces the risk of diseases spreading, although high standards of biosecurity can be easily breached with public access to areas adjoining outdoor pig paddocks. Acceptability to customers / maintain and improve living landscape Outdoor units (Edwards, 2005), and especially animals grazing common land, are particularly at risk of diseases being introduced and spread. Isolated units with all animals confined indoors are at least risk of disease outbreak if good biosecurity measures are practiced. Outdoor systems are at increased risk of infection from wild animal populations (e.g. bovine tuberculosis from badgers; Ward et al., 2006). 3.2. High health status, low mortality High animal health status is the goal of all livestock farmers. Low rates of mortality among productive animals mean fewer replacement breeding animals, lower production costs, and lower costs of disposal of fallen stock. High health status can be more difficult to achieve in outdoor systems than indoor systems, because there is less opportunity for control of conditions and increased risk of transfer in of diseases.

Effect on livestock output or performance Esslemont and Kossaibati (2002) summarise the costs of disease in UK dairy cows. In addition to the direct veterinary costs associated with, e.g. mastitis, they also highlight the costs of loss of production from the animal. Essentially, healthy animals are faster growing and higher yielding than unhealthy or sick animals. Sick animals should be treated as quickly as possible, or if treatment is considered to be economically unviable, culled from the herd or flock to prevent spread of infectious diseases to other animals.

Provision of safe, good quality food It is of the highest importance that animal products destined for human consumption are derived from healthy animals. Many zoonoses can be transmitted through the general population via the consumption of infected meat, milk and eggs, e.g. brucellosis, tuberculosis, listeriosis, salmonellosis, E. coli O157, while others can be transmitted through contact to farm workers, e.g. orf and leptospirosis. Although correct processing of animal products can reduce the risk of infection in human consumers (e.g. pasteurisation and cooking), farm workers can be at increased risk because of their daily contact with livestock. High animal health status in the herd or flock reduces this risk. 3.3. Use of prophylactics (vaccines, dips etc.) and medications Animal health is of prime importance to livestock producers. Primary prophylaxis, to prevent development of a disease or disorder, is generally regarded as better than treatment, both for animal health and economically. However, routine use of medications when not required can lead to resistant populations of disease-causing agents, and to environmental contamination (Spratt, 1997; Boxall et al., 2004).


Consistency with legal requirements Since January 1 2006, the use of antibiotics for non-medicinal purposes has been illegal in the EU (regulation 1831/2003/EC) because of concerns that widespread use could lead to increased antibiotic resistance of pathogens responsible for human diseases. Reduced non-medicinal use of antibiotics for animal production is also occurring voluntarily in other parts of the world (e.g. USA; Baker, 2006). Until recently, under the Sheep Scab Order 1986 and the Sheep Scab (National Dip) order 1990, prophylactic treatment of all sheep for sheep scab (caused by the mite Psoroptes ovis) was mandatory. Following the introduction of the Sheep Scab Order (1997) it has become a criminal offence if owners or keepers of sheep fail to treat visibly affected sheep and all others in the flock. Prophylactic treatment for some diseases, although developed, is not available to UK farmers except in certain circumstances as a matter of national or EU policy. Notable examples are vaccines for Foot and Mouth Disease and Bluetongue.

Animal health status Vaccination of livestock is widespread in the industry. Some highly effective vaccines exist for a wide range of diseases in different species, and many farmers use them because the cost of vaccination is far less than the loss of income through disease. It also ensures that animals require less treatment for diseases to which they might otherwise become infected with, and which may be zoonotic. Some farm assurance schemes require vaccination, for example against Salmonella enteritidis for laying hens in the British Lion Quality Code of Practice. Some antimicrobials are used prophylactically, particularly during the rearing of young poultry to prevent diseases such as first week septicaemia, mycoplasma infection and coccidiosis. 3.4. Active use of farm health plans Herd and flock health plans are often prepared and in place on a farm, and are frequently required as part of farm assurance schemes (e.g. Red Tractor farm assurance; www.redtractor.org.uk). However, there is probably scope to ensure health plans are more actively used and valued on livestock farms.

Animal health status The production and regular review of herd and flock health plans on livestock farms is consistent with a preventative approach to disease control. Depending on the species, health plans should take into account components of animal health such as foot care and trimming, vaccination plan, biosecurity measures, protocols for the disposal of dead stock, and methods of identification and treatment of sick stock.

Protection against animal disease impact The Animal Health and Welfare Strategy for Great Britain, promoted by Defra, the Scottish Executive and the Welsh Assembly Government (Defra, 2004) highlights animal health planning as a central component, with premise of disease prevention being better than a cure.


Efficient use of resources Prevention of disease through active use of farm health helps to target resources, particularly labour and to a certain extent, buildings. Regular monitoring of treatment strategies with corrective action if necessary ensures timely response to fluctuating health patterns, again ensuring resources are used most effectively. Performance and economic benefits from healthy versus unhealthy livestock with greater losses are well documented. Healthy production creates a motivated workforce, while the converse results in demotivated staff spending more time treating sick animals and coping with higher mortality. 3.5. Prompt use of veterinary services Veterinary services can be expensive and a call-out may cost more than the economic value of the animal being treated. At the same time, for expensive livestock such as cattle and breeding animals prompt veterinary attention for sick, poisoned or injured animals is very important. Treating an animal as early as possible in the course of a disease or disorder, at sub-clinical stages, is often the most effective.

Consistency with legal requirements The Welfare of Farmed Animals (England) Regulations 2007 states “Any animals which appear to be ill or injured must be cared for appropriately and without delay; where they do not respond to such care, veterinary advice must be obtained as soon as possible”. Animal welfare standards Regular and prompt veterinary intervention is consistent with maintaining high animal welfare standards. For pig and poultry production, regular intervention from a specialist vet will help to maintain health at the herd or flock level. Animal health status Regular and prompt veterinary intervention is consistent with maintaining a higher health status.

Protection against animal disease impact The prompt use of veterinary services for an individual animal for treatment can help to reduce the risk of infection in other animals. 3.6. Routine use of other health services (e.g. foot trimmers) Although most livestock farmers are very capable at husbandry, veterinary surgeons are the primary health practitioners on livestock farms and must be used to obtain prescription only medicines (POM) and to carry out specialist procedures such as surgeries. Some health services, however, may be contracted to other individuals. Typical examples are services for foot trimming, beak trimming and artificial insemination.


Animal welfare standards Hot blade beak trimming has been undertaken to reduce the risk of feather-pecking and cannibalism among birds (Kuo et al., 1991; Cunningham, 1992) although it is also associated with reduced feed intake and some pain at the time of the procedure (Cunningham, 1992). The practice is due to be banned at the end of 2010 although infra-red beak treatment may continue to be permitted. Tail-docking and teeth-clipping in pigs is used to reduce the risk of tail-biting or damage to other pigs, although this too is associated with pain during the procedure (Sutherland et al., 2008).

Animal health status Lameness is a major problem in livestock, particularly dairy cows (Blowey, 2005; Rutherford et al., 2009), and can affect milk production (Warnick et al., 2001) and fertility (Garbarino et al., 2004). The routine treatment of dairy cattle by vets as compared with professional foot trimmers was found to be no more sophisticated, but generally more expensive (O'Callaghan Lowe et al., 2004), but this is likely to reflect the numbers of animals seen on a visit and the cases seen requiring treatments that only vets have authority to employ (i.e. use of anaesthetics and analgesics, when required).

Effect on livestock output or performance Good fertility is critical for any breeding stock. Fertility of dairy cows is particularly important for some dairy farmers who operate strictly planned calving patterns. Some farmers use professional insemination services, although timing of insemination may be improved by farmers carrying out insemination themselves without little difference in success rate (Schermerhorn et al., 1986; Buckley et al., 2003). Reliance on AI in the pig industry has grown dramatically with the majority of producers carrying it out on a routine basis, both as a means of maintaining or generating breeding stock but also of enhancing quality of slaughter stock. 3.7. Carcass disposal via approved on-site incinerator Fallen stock must not be buried or burnt in the open to reduce the risk of disease transmission through water or air pollution. Depending on the size of the operation and the size and number of carcasses to be disposed of, an approved on-site incinerator may be the most economic form of fallen stock disposal.

Farm energy consumption On-farm incinerators can be fuelled by a number of fuels, including diesel fuel, liquid petroleum gas, natural gas and biofuels. In addition, there are none of the transport costs associated with the movement of carcasses to an off-site location.

Odour and nuisance emissions and cleanliness of the local environment Some odour inevitably results from the use of on-site incinerators, even if legal requirements are met (see below).


Protection against animal disease impact On-farm incineration can help with farm biosecurity measures, so that carcass removal vehicles are not entering farm premises, and dead livestock are not being transported away from the farm, both of which offer the threat of spreading disease (Blake, 2004). Pollard et al. (2008) recently listed commercial processing (including incineration) as the most preferred choice of carcass disposal in the event of an exotic animal disease outbreak (avian influenza).

Consistency with legal requirements Under the Animal By-Products Regulation (ABPR) (EC) No. 1774/2002, fallen livestock must be taken to or collected by an approved knacker, hunt kennel, incineration plant or rendering plant. On-farm incineration is permissible under the Regulation 1774/2002 so long as the incinerator is used to dispose only of carcasses or parts of carcasses and not other animal by-products (e.g. food waste) or other waste, otherwise authorisation must be obtained under the Waste Incineration Directive (2000/76 EC). In the England, Regulation 1774/2002 is enforced by the Animal By-Products Regulations 2005 ((SI 2005/2347) ABPR). To reduce the amount of noxious gases produced by an incinerator (Chen et al., 2003), all fumes must be heated to at least 850°C for at least 2 seconds. The fumes of every tenth burn must be monitored and recorded (automatically or manually) to ensure this occurs (Defra, 2006). 3.8. Carcass disposal via approved off-site methods As discussed in Section 3.7, to reduce the risk of environmental pollution (Kalbasi-Ashtari et al., 2008; Glanville et al., 2009) and disease spread, dead livestock must be disposed of in an approved manner, which does not include on-site burial, burning in the open or natural exposure (i.e. leaving dead animals out to be consumed by scavengers).

Farm energy consumption There is increased cost of transport to off-site facilities, but larger incinerators may operate more efficiently than on-site incinerators (i.e. have lower fuel costs per carcass disposed of). Some rendering plants now produce biodiesel from rendered animal fats so this could be used to fuel carcass collection vehicles.

Odour and nuisance emissions and cleanliness of the local environment No odour from incineration is produced on site if carcasses are taken off-site. However, secure on-farm storage is required to hold carcasses awaiting collection. Sealed air-tight plastic bins can help contain odours and are capable of being effectively cleaned and disinfected, but they are only of use for smaller carcasses, e.g. they are not suitable for adult pigs or large finishers, or for cattle. Efficiency of water use There is greater water usage with washing down carcass storage areas to maintain high health status. On-farm use of chemicals


There is greater disinfectant usage associated with washing and disinfecting carcass storage areas to maintain high health status.

Protection against animal disease impact Collection of carcasses can be a major biosecurity threat, with vehicles entering the farm to remove dead animals. For the highest level of biosecurity dead animals should be taken to sealed carcass collection bins that are sited on the perimeter of the farm. For smaller units, or for larger animals, and where maintaining the highest levels of biosecurity is not as important, collection of carcasses for disposal from the main farm may be the most convenient method.

Consistency with legal requirements As discussed in Section 3.7, fallen stock must be disposed of in a legally approved manner. In the US composting and biodigestion has been proposed as a means of carcass disposal (Keener et al., 2002; Glanville et al., 2006; Glanville et al., 2009), although this is not legal in the EU under EC Regulation 1774/2002. Therefore, under normal conditions fallen stock must be disposed of either by on-site incineration, disposed of at a local hunt kennel, or through collection by a knacker for off-site incineration or rendering. In the UK the National Fallen Stock Company (www.nfsco.co.uk) was set up to help livestock farmers dispose of animal carcasses when burial become an illegal method of disposal. 3.9. Use of biological controls for pests and parasites Biological control depends on using natural enemies for predation, parasitism, herbivory or physical mechanisms of managing problem pests of both plants and animals. Insects, mites, birds and rodents can act as vectors of disease for farmed livestock, as well as being causative agents in their own right, and therefore it is important to control them on livestock farms. Chemical controls (i.e. poisons) can be effective, although some pests, e.g. rats have developed resistance to pesticides such as warfarin-based rodenticides (Thijssen, 1995). Therefore, various methods of biological control may be used, which provides an alternative strategy to using chemical control methods (Hennessy, 1997). Biological control options are particularly suitable for organic systems, which have far fewer chemical control options than conventional farms (Cabaret, 2004). In egg production systems, a number of commercial products have been developed which use biological principles for the control of red mites and other insect pests.

Animal welfare standards Controlling pests and parasites of farm livestock leads to higher levels of animal welfare.

Animal health status Many (general) farms keep one or more cats as biological control agents of rodents. However, because cats themselves can act as vectors of disease or parasites (e.g. toxoplasmosis, toxocariasis), they require regular worming programmes and control of access to feed stores to prevent defecation in livestock feed.

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Flies can act as vectors of disease (e.g. Cryptosporidium; Szostakowska et al., 2004) on-farm, as well as causing irritation or disorders in cattle by biting. Biological control of fly larvae by using ducks in pig and dairy cattle facilities has been shown to be effective (Glofcheskie and Surgeoner, 1993). The use of parasitoid wasps, that infect fly pupae and therefore help to reduce fly numbers (Hogsette, 1999), has been shown to be effective on dairy farms (Skovgård, 2004), although success rate may depend on the location (McKay and Galloway, 1999). Gut parasites can be controlled biologically in a number of ways. The fungus Duddingtonia flagrans is able to trap and kill larvae of parasitic nematodes, such as Cooperia oncophera, which is a gut parasite in cattle (Larsen et al., 1997. This fungus has been isolated from the faeces of many livestock species (Larsen, 1999), and because it relies on physical methods of nematode control, is less prone to resistance build up in the target species (Larsen, 2000). Certain plant secondary compounds, such as alkaloids and condensed tannins, have been shown to be effective at reducing gut parasite load (Githiori et al., 2006). The physical structure of forage plants may also help reduce parasite infection, with for example, fewer larvae in the sward grazing horizon in red clover compared to ryegrass (Marley et al., 2006b). Poultry red mites (Dermanyssus gallinae) are common poultry parasites, and there is scope for biological control of them using predatory mites (Lesna et al., 2009)

Acceptability to customers Biological control, and a concomitant reduction in the use of chemicals to control pests, is likely to be highly acceptable to customers.

Effect on livestock output or performance A reduction in pests and diseases on farm should have no adverse effect on animal production. Feed production (forages and grains) is also open to biological control. A classic example of this is the use of an endophytic fungus (Acremonium loliae), which produces a number of alkaloids including the mycotoxins lolitrem A and B (Ball et al., 1995). In New Zealand the endophyte confers protection against the Argentine stem weevil, and without endophyte grass growth can be severely reduced. However, at high concentration the lolitrems can have a neurotoxic effect on grazing animals (leading to grass staggers). Although the endophyte is found in the UK (Lewis and Clements, 1986), it is currently not required for good grass growth due to the lack of pest such as the stem weevil.


4. Animal Nutrition

List of practices considered most important in the area of animal nutrition and considered in this section. 4.1 Use of home-grown protein crops 4.2 Feed mixed on site 4.3 Raw feed materials sourced on 'least cost' basis 4.4 Use of own-grown crops in compound feed 4.5 All feed purchased from compounder 4.6 Use of higher quality feeds for better efficiency 4.7 Use of permitted co-products 4.8 Use of phase feeding 4.9 Use of low crude protein diets 4.10 Use of enzymes, digestive enhancers and chemicals in feed 4.11 Use of feed systems that minimise physical wastage 4.12 Use of drinking systems that minimise water wastage 4.13 Use of own local water supply 4.14 Use of mains water supply 4.1. Use of home-grown protein crops The use of home-grown crops as a source of protein is not widespread in the pig and poultry industries, mainly because of the need to balance amino acids in the diet for high production rates and optimum efficiency. The pig industry is currently investigating alternative sources of home–grown proteins, principally new varieties of peas and faba beans with lower anti-nutritive factors, to reduce reliance on imported soya and therefore lower greenhouse gas emissions (the Green Pig Defra-LINK project). Additionally, use of liquid co-products with high protein content can also help reduce need for imported soya in liquid feeding rations. However, in the ruminant industries, particularly for dairy production and for finishing lambs and beef animals, high protein crops are often used as part of a diet. Soya imported into the UK is a major ingredient of compounds feeds for animals, and replacing this with a UK-grown alternative (e.g. lupins; Fraser et al., 2005; Partanen et al., 2006) would contribute reducing transport energy use and farmer costs. Soya production in South America has been a major driver for rainforest destruction (Nepstad et al., 2006), and therefore use of soya alternatives can help alleviate this problem. There is also a role for plant breeders to produce varieties of cereals with higher available digestible protein, reducing the need for imported protein balancers.

Farm ammonia emissions Without appropriate diet formulation, the high protein content and high digestibility of the proteins in ‘high protein crops’, particularly in ruminants, can lead to low rates of N use efficiency. In dairy cows, for example, N use efficiency of certain legume silages for milk production were 20% or less (Dewhurst et al., 2003b). Much of the remaining N is excreted in urine as urea, which is rapidly converted to ammonia. Therefore, care is needed to ensure that the nitrogen in high protein crops is used


efficiently and does not lead to more N leaching or N2O emissions from spreading slurry (Clayton et al., 1997).

Farm greenhouse gas emissions Many ‘protein’ crops are legumes, that require no artificial N fertiliser applications, which makes a significant contribution to UK N2O emissions (Smith et al., 1998). Legume high protein crops fit well into organic and other low-input farming systems. Wheat protein products produced from bioethanol plants (e.g. that run by Ensus Ltd on Teeside) can also partly replace purchased soya in livestock rations, potentially lowering GHG emissions, especially if that soya was imported from unsustainable sources, e.g. grown on deforested Brazilian land.

Animal health status High protein crops can help reduce the effect of intestinal parasites on grazing ruminants (Marley et al., 2005), either by supplying more protein to support the animals immune system, or through physical processes that prevent larval migration to the grazing horizon in the sward (Marley et al., 2006b).

Effect on livestock output or performance High protein crops such as red and white clover, lucerne, lotus, peas, beans and lupins may be grazed, ensiled or harvested for grain depending on the species, variety, and the intended use. Lambs grazing clover and lucerne swards grow more quickly than lambs grazing ryegrass pasture (Fraser et al., 2004). Although most red clover varieties are bred to express low concentrations of isoflavanoid compounds such as formononetin which can negatively affect ewe fertility, finishing lambs consuming high-formomonetin red clover grew more quickly than lambs consuming a low-formononetin variety (Moorby et al., 2004). Similarly ensiled legumes are allow higher growth rates in lambs (Marley et al., 2007) and are better able to meet nutrient requirements of pregnant ewes than ryegrass silage (Speijers et al., 2005). Beef steers also gain more weight during winter feeding when offered red clover silage compared with grass silage (Fraser et al., 2007b). Red or white clover silages may be mixed with another forage (e.g. grass or maize silages) to reduce the crude protein concentrations of the diet and to balance the protein with energy-yielding nutrients for improved performance in dairy cows (Bertilsson and Murphy, 2003; Dewhurst et al., 2003a; Moorby et al., 2009b) and beef steers (Fraser et al., 2003). Dairy cows fed a pea/wheat bi-crop silage performed not better than those offered a medium quality grass silage (Salawu et al., 2002), although in another experiment the use of similar crops enabled a reduction in concentrate feeds to be fed to dairy cows while maintaining milk production (Adesogan et al., 2004). Eating quality of meat from animals fed red clover silage was found to be reduced, compared to conventionally fed animals, in pigs (fresh meat: Johansson et al., 1999; or frozen: Jonsäll et al., 2000) whereas there was no difference in beef organoleptic qualities from animals that had red clover silage in the diet (Fraser et al., 2007b). The use of legume crops fits very well with organic (Partanen et al., 2006) and low input farming systems, relying on the fixation of atmospheric nitrogen, rather than


applications of chemical fertilisers, to produce protein in the crop and delivering nitrogen to the soil for use by other plants either mixed with the legumes or in subsequent crops in the same land area. 4.2. Feed mixed on site Pig and poultry operations rely heavily on bought-in concentrate feed for meat and egg production. Ruminant systems, particularly dairy production, also typically rely on concentrate feeds, although their use may be restricted to certain times of the year or production cycle (e.g. at lambing, or in early lactation only). Such concentrates may be purchased as a complete feed, or may be mixed on site using purchased ingredients and/or home grown ingredients. Liquid feeding systems for pigs typically involve on-site mixing (Lumb, 2002). The production of total mixed rations (TMRs) for cattle feed, in which forages (particularly silages) are mixed with other ingredients (either compound feeds, or more commonly straights, e.g. soya), is becoming increasingly common. Farmers mixing feeds on site, even for on-farm use only, which include certain additives, or products containing those additives (e.g. premixes), must register with the local Trading Standards office under Statutory Instrument No. 1872, “Feeding Stuffs (Establishments and Intermediaries) Regulations 1999.

Farm energy consumption There would be reduced energy (fuel) use and transport costs for finished feeds if mixes include home-grown ingredients, compared to a complete compound feed purchased from a feed manufacturer. However, energy consumption may be high for small batches of feed, and therefore costly on a pounds-per-tonne basis.

Farm ammonia emissions There is considerable scope to reduce N excretion and therefore reduce NH3 emissions by feeding livestock (particular cattle and pigs) to requirements by optimising their diets. See Sections 4.6, 4.8, 4.9 and 4.10.

Farm greenhouse gas emissions There is considerable scope to reduce N excretion and therefore reduce N2O emissions by feeding cattle to requirements by optimising their diets. See Sections 4.6, 4.8, 4.9 and 4.10.

Farm odour & nuisance emissions There is considerable scope to reduce N intake and therefore N excretion. This is likely to reduce odours originating from animal excreta. See Section 4.10.

Efficient use of resources On-farm losses are possible if mix ingredients (solid and liquid) are not stored appropriately or used before they deteriorate (e.g. through fermentation of liquid feeds, or through loss of activity of vitamins in premixes).


Protection against animal disease impact Biosecurity could be a problem if mobile equipment is used and is moved between operations. This risk could be offset to an extent if different sites, under the control of one operator, were of a similar health status, offering benefits of economy-of-scale. On the other hand, on-farm mixing of feed, compared with purchase of a complete compound feed, ensures knowledge of all ingredients used in that feed. 4.3. Raw feed materials sourced on 'least cost' basis In most livestock systems this has been the standard approach for many years. Economic sustainability is key to any farming system, although the cheapest feed is not necessarily the optimum if, for example, lower digestibility reduces growth rate or lactation performance. However, with appropriate nutrient analysis of feeds, together with costs associated with those feeds, appropriate rations can be formulated, typically using linear programming methods (e.g. Tozer, 2000). It should be noted, however, that least-cost rations that optimise livestock performance may also result in higher rates of pollutant excretion, and future ration formulation systems may need to take this into consideration, i.e. using a ‘least environmental-cost’ formulation. 4.4. Use of own-grown crops in compound feed Use of own-grown crops (particularly cereals) is common on mixed systems farms, and particularly on cattle farms. These crops can be incorporated into mixed feeds (Section 4.2), or could be incorporated into a compound feed if a local compounder is used.

Farm energy consumption Reduced transportation of complete feeds means that less fuel is used to move feeds. 4.5. All feed purchased from compounder This is the most common approach used by pig and poultry operations, particularly when feed contracts are negotiated by the operational centre for a number of large units at different locations. Ruminant systems rely on forages grown on the farm, although concentrate supplement feed may be purchased as a compound feed ready to give to the animals.

Efficient use of resources Economies of scale mean that compound feeds purchased from a feed manufacturer may be cheaper than straights ingredients for on-farm mixing. Industrial equipment, high levels of quality control, more regular analysis of feed ingredients, and access to a greater range of raw materials can also mean more precise formulation (particularly at the level of amino acid balance) is achieved by the feed compounder. For large operations with large numbers of animals at different physiological stages (mainly pigs and egg-producing poultry), purchasing a range of compound feeds to


meet the specific needs of each category of stock and providing accurate phase feeding may be easier and more efficient than mixing the same range of diets on-farm. On the other hand, dairy farmers with average numbers of animals in a tight calving pattern may find it easier and more efficient to alter feed mixtures more frequently to meet animals requirements by using on-farm mixed diets (which may include purchased compound feed), rather than purchasing a single ‘general purpose’ concentrate in bulk.

Farm energy consumption Initiatives such as sourcing cereals from the farmer-owned co-operative grain merchant (Openfield) within a 50 mile radius of the feed mill (BOCM Pauls) used to manufacture pig diets for the country’s largest pig producer (BQP) is an example of reducing transport energy costs in the pork supply chain (via meat processor Dalehead Foods) for Waitrose supermarkets. 4.6. Use of higher quality feeds for better efficiency In any livestock system, lower quality feeds (e.g. low digestibility, poor nutrient balance), tend to reduce the efficiency of production (growth, lactation). For animals at maintenance, these might be appropriate, but for high performance animals (fast growing livestock – particularly young pigs and poultry – and high genetic merit dairy cows) for which feed intake and digestibility are frequently the limiting factor to production, high quality feeds are typically used. The definition of what constitutes a high quality feed clearly depends on the type of livestock (species, age, sex, physiological stage) to which it is being fed. For monogastrics, the use of synthetic amino acids and enzymes in the diet in conjunction with highly digestible ingredients increases overall feed quality and thus the efficiency of feed utilisation, thereby reducing pollutant excretion (Lenis and Jongbloed, 1999; Han et al., 2001; Aarnink and Verstegen, 2007). 4.7. Use of permitted co-products Co-products (or by-products) are residues or ‘wastes’ from a manufacturing process designed primarily for another product. Such feeds used in the ruminant-livestock industry are meals and grains produced following oil, sugar or starch extraction (e.g. sugar beet pulp, rapeseed meal, distillers grains and maize gluten meal). The inclusion of such feeds in livestock diets is very common, particularly in ruminant diets, and some are highly nutritious with high protein concentrations and useful concentrations of residual oils, sugars or starches. Appropriate use of co-products can reduce the reliance on feeds (e.g. cereals and soya) that could otherwise be used for human consumption, thus helping to reduce the environmental impact of livestock farming (Elferink et al., 2008). In the pig industry, liquid feeding of pigs is commonplace on many units. This is usually based around a number of co-product ingredients available either locally or nationally. These would typically include by-products available from human food manufacturing and processing sites including those used for starch-processing, soft drinks, potato processing, brewing, dairy products and confectionary. Local availability influences the choice of co-products used for animal feeds, such as the use of whey to finish pigs in the south-west of the UK, and the use of brewer’s grains in distillery-rich parts of Scotland.


Recycling/composting, and landfill The use of co-products as animal feed diverts them from land-fill. Some co-products are not permitted in animal feeds in the EU, for example meat and bone meal (Regulation (EC) No. 999/2001), and are frequently incinerated as a source of renewable energy. 4.8. Use of phase feeding Livestock at different growth stages or stages of the reproductive or lactation cycle have different optimum feed requirements. However, because of limited labour and housing facilities, livestock with different feed requirements are often grouped together (e.g. in the same house) and receive the same ration at a feed line or via a single feed delivery auger from a bulk bin for each house. As a result, some stock will receive higher levels of N (and P) than they can utilise efficiently and will excrete the surplus. Greater division and grouping of livestock on the basis of their feed requirements (phase feeding) allows more precise formulation of individual rations. In pigs this is more easily achieved with batch production compared with continuous production. However, research on phase-feeding in liquid feed systems for pigs failed to demonstrate a tangible cost benefit (Gill, 2005). This will reduce N (and P) surpluses in the diet and reduce the amounts excreted. Phase feeding groups for dairy cows, as an example, would include:

i) Far-off dry cows (until 14-21 days precalving) ii) Close-up dry cows (from 14-21 days precalving) iii) Early lactation (fresh) cows (for 1-2 weeks postcalving) iv) High production first-calf heifers v) High production older cows vi) Low production/excess body condition cows

Movement of cows between groups, particularly the lactation groups, will depend on the production potential of individual cows, body condition scores and the length of the reproduction cycle. Feeding lactating dairy cows a concentrate allowance based on milk yields (i.e. to their requirements) through in- or out-of-parlour feeders is commonly practiced in the UK dairy industry. Examples for other livestock species include:

i) Broilers: grouped into starter, grower and finisher rations ii) Layers: grouped into early/peak lay, mid lay, and end lay iii) Sows: grouped into dry and lactating sows iv) Weaner pigs: grouped into creep starter, link, and early grower v) Grower-finisher pigs: grouped into grower, grower-finisher, and two-stage

finisher diets, e.g. Stage 1 (higher crude protein), and Stage 2 (lower crude protein) for pigs finished at heavier weights


Farm ammonia emissions Phase feeding allows more precise matching of the ration to the individual animal’s nutritional requirements. Nutrients are utilised more efficiently and less of the dietary N is excreted, thereby reducing the N content of manures (Lee et al., 2000; Pope et al., 2002; Pope et al., 2004). This reduces the amount of N available for loss via ammonia emission (Cole et al., 2005a) from the point of excretion onwards (i.e. during livestock housing, manure storage and following land spreading). For cattle and sheep, where a large part of the diet is likely to be delivered through grazing forages, emission reductions are likely to be difficult to deliver practically.

Risk of water contamination incidents Reducing the amount of N excreted from livestock will reduce the potential for diffuse losses to water (ammonium-N in surface drainflow/run-off and nitrate leaching) and for gaseous emissions of nitrous oxide. If phase feeding also reduced P intake, there would be additional benefits of reducing diffuse losses of P to water. Water quality Reducing the amount of N excreted from livestock will reduce the potential for diffuse losses to water (ammonium-N in surface drainflow/run-off and nitrate leaching) in water catchment areas. Efficient use of resources Matching dietary protein to animal needs avoids overuse of protein and saves feed costs. 4.9. Use of low crude protein diets Farm animals are often fed diets with higher than recommended contents of crude protein (CP) as a safeguard against a loss of production arising from a deficit through inaccurate analysis and/or formulation. In practice, however, surplus N is not utilised by the animal and is excreted. Restricting diets to recommended levels of N can limit the amounts excreted without affecting animal performance. Use of nutritional advisors and feed companies that use ration formulation software with the most up-to-date advice (e.g. Feed into Milk for dairy cows; Defra LINK project LK0604; Offer et al., 2002). In all livestock N excretion can also be reduced by increasing the digestibility of the ration so long as the biological value of the absorbed amino acid mixture is appropriate for the productive requirements; amino acids supplied in excess of requirements may contribute to the energy metabolism of the animal, but excess N is excreted. Benefits will be greatest on indoor cattle units where conserved forage constitutes a large part of the diet, and diets must be formulated with supplements to ensure appropriate total N supply. The diets of pigs and poultry are largely well controlled and formulated to contain minimum N requirements in combination with balanced essential amino acids to maximize production. Therefore, there is limited scope for further reducing the N content of pig and poultry diets without reducing output. The greatest challenges exist on cattle farms feeding a largely forage diet (although developments in plant breeding to produce forages aimed at improving N utilisation by ruminants continue).


Within the dairy sector there is already a focus on lowering total diet crude protein content, optimising protein:energy balance in the rumen and supplying adequate metabolisable protein. Reducing the crude protein content of the diet may be a significant challenge in areas relying on grass silage, in which case there is increased reliance on the use of energy-rich supplements (i.e. cereal grains). Also, matching requirement to performance has cost, labour and housing implications on many farms. There is more potential for improved ration formulation when animals are offered formulated diets (i.e. indoors), when there is greater control over what can be given to the animals. Jonker et al. (2002) found that North American dairy farmers fed on average 6.6% more protein than recommended by published guidelines (NRC, 1989), leading to a 16% increase in urinary N excretion, and the same is probably true for the UK where milk producers are keen to maintain high milk protein yields. Because urea in urine is a major source of N2O emissions from grazed pastures increasing the WSC concentrations relative to proteins in grazed forages is likely to reduce direct N2O emissions from grazing animals.

Farm ammonia emissions Reducing the amount of N excreted will also reduce the potential for losses of NH3 from urine (Cole et al., 2005a) and manure management, which are estimated to be in the range 3-10% (Defra project WT0706). However, where maize is included in cattle diets to improve nutrient use efficiency, it is important to ensure that land management practices do not result in negative impacts on water quality through enhanced nutrient and sediment losses in run-off. For pigs and poultry, considerable steps have already been made through the use of synthetic amino acids (although not in organic units) (Lenis and Jongbloed, 1999; Han et al., 2001). There is limited scope for further reducing the N content of pig and poultry diets without reducing productive output (e.g. Defra project LS3601). There are concerns that reducing nutrient inputs may also have adverse effects on reproductive performance and carcass quality. The scope to use more digestible materials in broiler diets is also very limited as most diets already employ feed materials of high digestibility.

Farm greenhouse gas emissions An increase in the efficiency of livestock N use efficiency of up to 10% is predicted to reduce direct N2O emissions by about 6% (Defra project IS0214; Del Prado and Scholefield, 2008). There may be a decrease in CH4 emissions from ruminants, depending on the diet formulation and level of feed intake. Farms that seek to reduce the N content of the diet by replacing grass silage with maize silage may also reduce CH4 emissions.

Farm odour & nuisance emissions The emission of malodorous compounds from manures is also likely to be reduced as a result of lowering the concentration of N in excreta. Odorous compounds originating from livestock units originate from a number of sources including feeds, the animal bodies, and their excreta (Le et al., 2005). In general, the most objectionable odours originate from compounds arising from the production,


handling, storage and spreading of manures, and many are generated through microbial action (Spoelstra, 1980; Mackie et al., 1998). These include ammonia, amines, sulphurous compounds, volatile fatty acids, indoles, skatole, phenols, alcohols, and carbonyls (Le et al., 2005).

Water quality On dairy farms reducing the crude protein content of the diet from 18 to 14% (with corresponding increases in efficiency of utilisation) was estimated by Cuttle et al. (2007) to reduce NO3 leaching by 5-6%. 4.10. Use of enzymes, digestive enhancers and chemicals in feed This is widespread across the pig industry, and is increasingly used in the poultry industry. Enzymes such as phytase can increase the dietary availability of phosphorus, thereby reducing the concentration that needs to be included in the diet, thus reducing P excretion (Nahm, 2004). Feed additives based on yeast products are widely available for ruminants (dairy, cattle and sheep) and may be added as part of a total mixed ration or included in a concentrate feed. Sodium biocarbonate and other alkaline compounds are frequently added to ruminant (particularly dairy cow) diets to reduce the risk of low rumen pH values (acidosis; Gokce and Imren, 1998) that may otherwise develop with high levels of concentrate feeding (Araba et al., 2002). Protection against animal disease impact Organic acids can be added to diets for laying hens to provide protection against Salmonella. Organic acids, supplied either in feed or via the water delivery system, are also used to combat Salmonella incidence, for example in weaned and growing pigs.

Farm ammonia emissions McCrory and Hobbs (2001) reviewed the use of feed additives to reduce ammonia emissions from livestock wastes and concluded that most generally performed poorly, possibly because any mechanism of action is relatively short-lived.

Farm odour & nuisance emissions Digestive additives are also available that claim to reduce offensive odours from livestock wastes. The review by McCrory and Hobbs (2001) also concluded that these are generally ineffective for odour control.

Water quality Phosphorus is a key pollutant of water with agriculture as a major source of this pollutant. Methods of reducing the use of P in livestock feeds, thereby reducing its excretion into manures, are critical in terms of reducing eutrophication of fresh water courses (Bechmann et al., 2005). Animal health status Digestive enhancers are used in weaned pig diets, particularly, to combat colitis and looseness and onset of enteric disease.


Effect on livestock output or performance Phytase in poultry feeds helps to maximise the use of phytate-P, but does not improve the efficiency of protein utilisation in chicks (Augspurger and Baker, 2004). On the other hand, productivity is unaffected. Phytase supplementation of pigs achieves similar results (Baidoo et al., 2003). Dietary supplements based on yeast (Saccharomyces cerevisiae, frequently sourced as a bioproduct of the brewing industry) are designed to improve digestive function (particularly rumen fermentation) in ruminants, but they have also been investigated in pigs (Mathew et al., 1998). Much work has been done to investigate their use and potential mode of action, although the effects on animal productivity have been found to be extremely variable. The main mode of action of live yeast cultures is probably through a supply of growth factors to rumen microbes and oxygen-scavenging that makes the rumen more anaerobic (Fonty and Chaucheyras-Durand, 2006). However, some studies with sheep have failed to find effects on fermentation, digestion and amino acid flow from the rumen when fed with maize stover diets (Angeles et al., 1998) or sugar cane tops (Arcos Garcia et al., 2000). Likewise, little effect of yeast supplementation has been found on growth rates of growing steers fed tropical forages (Cabrera et al., 20000). In dairy cows, microbial protein outflow from the rumen was unaffected by supplementation of grass silage diets with yeast cultures, although undegraded dietary N outflow increased, potentially as a result of changes in rumen outflow rates (Carro et al., 1992). Similarly, little effect of yeast culture supplementation has been observed in dairy cows offered diets based on maize silage (Doreau and Jouany, 1998) or grass silage and barley (Huhtanen, 1991). On the other hand, bacterial amino acid profile has been found to be affected by supplementation of dairy cow diets with yeast culture (Erasmus et al., 1992). When offered in combination with the ionophore monensin, yeast culture seems to alleviate a reduction in feed intake of early lactation dairy cows offered monensin alone (Erasmus et al., 2005). Feeding sodium bicarbonate to ruminants, particularly those fed on high concentrate diets that may induce acidosis at high rates of feed intake, can improve productivity in sheep (e.g. Tripathi et al., 2004) by increasing microbial protein production (Newbold et al., 1991). Feeding sodium bicarbonate to cows fed on diets based on maize silage was found to have significant beneficial effects (Hu and Murphy, 2005) but not when fed with diets based on other forages or at grazing (Clayton et al., 1999). 4.11. Use of feed systems that minimise physical wastage This is very widely adopted by livestock farms. The production and purchase of animal feed is one of the largest costs of any livestock operation, and therefore efficient utilisation that minimises physical wastage is very important for the economic sustainability of livestock production.

Effect on livestock output or performance The aim of livestock production systems is to allow animals to express their genetic potential for meat, milk or egg production. This typically consists of encouraging animals to consume as much feed as they require for this purpose, and therefore


any restriction to feed intake can reduce livestock performance efficiency. Feed barriers in indoor cattle systems, for example, that reduce bullying and competition between individuals can help enable feed intake in subordinate animals (Endres et al., 2005; Huzzey et al., 2006). Likewise, strip grazing of fresh pasture using moveable (typically electrified) fencing is widely used to prevent damage and soiling of fresh pasture. For pigs, liquid feeding systems give improved performance over dry or pelleted feeds when offered at ad libitum rates (Canibe and Jensen, 2003; Hurst et al., 2008), and liquid feeding produces less waste than dry feeding (Gill, 2004). Sow rolls or biscuits are usually fed in the outdoor systems as they can be distributed to sows in paddocks mechanically without shattering and remain intact whilst on the ground with less feed wastage. 4.12. Use of drinking systems that minimise water wastage This is standard practice in most livestock operations, not only to reduce the amount of water used, which has an associated economic and environmental cost, but also to ensure livestock are not unnecessarily wet, which has important welfare implications. Keeping bedding dry also makes it lighter and easier to move when mucking out. Farm ammonia, dust and odour and nuisance emissions Keeping litter and manure as dry as possible is essential in reducing ammonia emissions in poultry systems and in minimising odour levels. However, dry litters in particular may lead to increased levels of dust.

Animal welfare standards The Welfare of Farmed Animals (England) Regulations (2000) require all housed livestock (other caged laying birds) to have access to an area that is well-drained or well maintained with dry bedding. Therefore, the use of drinking systems that keep the indoor environment dry is of paramount important. For some animals there is a need to ensure that natural behaviour can be adequately expressed, e.g. for ducks there is a need to ensure that open water is available to allow bathing (i.e. bath, trough or shower) in addition to drinking (i.e. via a nipple drinker) (Defra project AW0223).

Effect on livestock output or performance Livestock need access to drinking water to prevent dehydration. Reduced water intake results in a reduction of feed intake (e.g. Utley et al., 1970). The measurement of daily water intake is important, both to ensure adequate supplies and as an easily achieved indicator of imminent health problems in large groups of livestock (e.g. pigs and poultry). Use of real-time data-logging systems that monitor water usage in pig units have established a clear correlation between lower water intake and onset of disease/health problems. 4.13. Use of own local water supply


Some livestock, particularly cattle and sheep in upland areas, depend entirely on natural water supplies for drinking water. In areas where mains water is available, the high cost of purchasing it means that use of a natural water supply is an option used by some livestock operations (Groves et al., 2002). This is typically achieved using a borehole to access underground water supplies. Assuming suitable groundwater is available, an abstraction licence is required if more than 20m3 per day is going to be pumped. There are high establishment costs associated with drilling a borehole or tapping into a natural spring, but once these have been met, the cost of water used can be much lower than purchasing mains supplied water. There is a need to ensure that water used for drinking is clean and not contaminated by pathogens or toxins. A water treatment plant may need to be installed to ensure clean water. Natural water supplies may also be used for cleaning, in addition to, or instead of the use of mains water. Efficiency of water use A proportion of mains water leaks from pipes between the source and the end user. Use of local water supplies potentially reduces this inefficiency. Contamination of water courses Allowing livestock direct access to water courses for drinking or through lack of fencing can lead to contamination by defecation and urination, and contamination through erosion of soils assisted by poaching. This can lead to contamination of water with pathogens (Baxter-Potter and Gilliland, 1988; Donnison et al., 2004) as well as increasing the nutrient content that can lead to eutrophication. Fencing off stream/river banks can substantially reduce bank erosion, inputs of N, and pathogens (Defra projects ES0121 and ES0203), although this would require alternative methods of providing drinking water to the livestock, such as piping (by gravity or by using a pump) stream water into a trough. 4.14. Use of mains water supply It has been known for many years that a good supply of fresh, clean water is essential for all animals, including cattle (McLachlan, 1930). Statutory Instrument 2000 No. 1870 (The Welfare of Farmed Animals (England) Regulations 2000) stipulates an adequate supply of fresh water must be made available to all farm animals. Lactating dairy cows in particular require large quantities to support milk production. Using a mains water supply is the standard approach to providing livestock with a clean source of drinking water, and, because of the use of drinking troughs, bowls or drinkers, should also safeguard natural water courses that animals would otherwise have to access. It is important that back-flow valves are fitted to supply pipes because water pressure may not be sufficient to supply large outdoor pig units unless overnight storage tanks are used.

Risk of water contamination incidents If livestock have access to a natural source of water then there is a high chance of them urinating or defecating in it, leading to contamination. Animals should therefore be excluded from accessing natural water supplies if possible. However, in some


outlying areas of a farm, particularly in the uplands, there may be no mains water supply, and natural streams and other water supplies may be the only option for water availability for some cattle and sheep.

Protection against animal disease impact Some diseases, such as tuberculosis and Johne’s disease, E. coli, Listeria, and Salmonella infections, can be spread through contaminated water. Therefore, use of regularly cleaned drinking troughs supplied with a mains water supply will minimise the risk of spread disease within a herd, and also between herds that might share a water supply.

Environmental benefits Prevention of livestock access to natural water courses will reduce the risk of contamination, reducing the impact of farming on the natural environment.

Provision of safe, good quality food Using a mains water supply will reduce the risk of certain diseases in cattle herds, some of which can be transferred to humans in infected meat and milk. It will also reduce the risk of zoonotic infections in humans using the same water resources (e.g. rivers) if cattle are allowed access to them to drink.


5. Nutrient Management

List of practices considered most important in the area of nutrient management and considered in this section. 5.1 Reduce fertiliser use 5.2 On-site solid manure storage in a farm midden 5.3 Field storage of manure prior to spreading 5.4 Frequent removal of manure from house 5.5 Use of manure on site of production as part of 'whole farm' approach 5.6 Active nutrient management planning 5.7 Spread manures to land in compliance with a Manure Management Plan 5.8 Time manure / slurry applications to land to maximise fertiliser value and

minimise pollution 5.9 Methods of manure application to land: broadcast on land, no

incorporation 5.10 Methods of manure application to land: rapid incorporation 5.11 Use of mechanical separation of manures and slurries 5.12 Capture of dirty water in covered stores 5.13 Capture of dirty water in un-covered stores 5.14 Use of covered slurry stores 5.15 Integral store and cover (bag) 5.16 Use of aerators for slurry systems 5.17 Use of nitrification inhibitors 5.18 Use of urease inhibitors 5.19 Account taken of land/receptor/weather considerations regarding

application practices 5.20 Account taken of cross compliance, including local restrictions e.g. NVZ 5.21 Use of anaerobic digesters for manure 5.1. Reduce fertiliser use There are two potential levels of reduction in inorganic fertiliser use. The first assumes fertiliser application beyond what is actually required for optimum (economic) crop growth and is most likely to occur in intensive grassland systems. Fertiliser application rates may be reduced to appropriate levels through the use of a recognised fertiliser recommendation system (e.g. RB209 (Defra, 2010), PLANET (Planning Land Applications of Nutrients for Efficiency and the Environment; www.planet4farmers.co.uk). These should take account of the following factors:

• Soil nutrient supply based on soil analysis or climate, previous cropping and soil type.

• Crop nutrient requirements for a given soil and climate. • Crop requirements for nutrients at various growth stages. • The amount of nutrients supplied to the crop by added manures and by

previous manure applications. • Soil pH and the need for lime.


• Adoption of a fertiliser recommendation system will reduce the risk of applying more fertiliser nutrients than the crop needs and will minimise the risk of excess N in the soil at risk of N2O losses.

The second level of reduction would be below recommended fertiliser application rates, and is likely to result in less-than-optimum rates of crop (or grass) growth.

Farm greenhouse gas emissions In both situations, nitrous oxide emissions are likely to be reduced as a result of less nitrification of fertiliser N (Moorby et al., 2007). Greenhouse gas emissions from fertilisers contribute largely derived ultimately from fossil fuels (with a large proportion being natural gas; ), which are used to provide energy for their production. Approximately 60% of the total energy used by UK agriculture in 2004 was indirect inputs, 31% of which was for fertiliser manufacture (Defra project AC0401).

Risk of water contamination incidents Reducing fertiliser use below recommended application rates will likely reduce the amounts of N and P leached from soils into water courses. The reduction in losses will depend on the soil type and therefore water infiltration rates (Cuttle et al., 2007).

On-farm use of chemicals Reduced fertiliser application rates will directly reduce the amounts of fertiliser chemicals used on a farm. 5.2. On-site solid manure storage in a farm midden

Farm ammonia emissions Storing farmyard manure (FYM) removed from straw-bedded cattle or pigs for a period of at least 3 months prior to spreading reduces the quantity of readily available nitrogen in the FYM at the time of spreading and thereby reducing the potential for ammonia loss at that stage, such that emissions from storage and spreading are less than that from the spreading of ‘fresh’ FYM. During open-air storage of the FYM, there will be losses via ammonia volatilisation, but readily available nitrogen will also be immobilised in straw and lost via denitrification (following a nitrification stage), the products of which are the gases nitrous oxide, nitric oxide and dinitrogen (the ratio in which these gases are produced will depend upon conditions in the FYM heap). The composting processes, and resultant emissions, depend on the density, and therefore porosity, of the manure pile (Veeken et al., 2002). This is most effective at reducing ammonia emissions when applied in situations where the FYM is not rapidly incorporated into the soil following land application, i.e. it is left on the surface. Spreading ‘fresh’ manure direct from the animal house, or sheeting manure during storage prior to land application are the most appropriate management strategies for situations where the manure is to be rapidly incorporated into the soil following field application.


Experimental studies have shown a wide range in the effectiveness of this method at reducing ammonia emissions compared with the surface spreading of ‘fresh’ FYM, depending on the relative rates of gaseous losses during storage and the extent to which other nitrogen transformations occur (mineralisation/immobilisation). Overall, the data indicate a mean reduction efficiency of about 30% where stored FYM (compared with ‘fresh’) is not incorporated into the soil following land application (Defra project WA0716; Chadwick, 2005; Sagoo et al., 2007).

Farm greenhouse gas emissions Storing FYM will result in increased emissions of nitrous oxide and methane, although the magnitude is uncertain. Turning straw-rich pig manure to aerate it can reduce methane and N2O emissions (Szanto et al., 2007).

Risk of water contamination incidents Uncontained leachate from FYM heaps represents a pollution risk to surface and ground waters. Storage in a purpose-built which enables effluent collection and storage would minimise this risk. 5.3. Field storage of manure prior to spreading

Farm ammonia emissions Storing farmyard manure (FYM) removed from straw-bedded cattle or pigs for a period of at least 3 months prior to spreading reduces the quantity of readily available nitrogen in the FYM at the time of spreading and thereby reducing the potential for ammonia loss at that stage, such that emissions from storage and spreading are less than that from the spreading of ‘fresh’ FYM. During open-air storage of the FYM, there will be losses via ammonia volatilisation, but readily available nitrogen will also be immobilised in straw and lost via denitrification (following a nitrification stage), the products of which are the gases nitrous oxide, nitric oxide and dinitrogen (the ratio in which these gases are produced will depend upon conditions in the FYM heap). This is most effective at reducing ammonia emissions when applied in situations where the FYM is not rapidly incorporated into the soil following land application, i.e. it is left on the surface. Spreading ‘fresh’ manure direct from the animal house, or sheeting manure during storage prior to land application are the most appropriate management strategies for situations where the manure is to be rapidly incorporated into the soil following field application. Experimental studies have shown a wide range in the effectiveness of this method at reducing ammonia emissions compared with the surface spreading of ‘fresh’ FYM, depending on the relative rates of gaseous losses during storage and the extent to which other nitrogen transformations occur (mineralisation/immobilisation). Overall, the data indicate a mean reduction efficiency of about 30% where stored FYM (compared with ‘fresh’) is not incorporated into the soil following land application (Defra project WA0716; Chadwick, 2005; Sagoo et al., 2007).


Farm greenhouse gas emissions Storing FYM will result in increased emissions of nitrous oxide and methane, although the magnitude is uncertain.

Risk of water contamination incidents Uncontained leachate from FYM heaps represents a pollution risk to surface and ground waters. Field storage where effluent is not collected would increase this risk because it may be difficult to ensure that there are no field drains nearby. 5.4. Frequent removal of manure from house For dairy cattle housed in a cubicle house, increasing the frequency of cubicle passage scraping will reduce the time that urine and faeces remain in the passage and thus reduce the amount of time for emissions to be given off. Similarly, for indoor pigs, frequent removal of slurry from below slatted-floor storage pits to an outdoor covered store will reduce the emissions from the slurry. Birds excrete excess N as uric acid (which is readily available N) and organically bound N. The hydrolysis of uric acid to ammonia is generally more prolonged than the rapid hydrolysis of urea, so significant emissions of ammonia may take one or more days to develop (depending also on temperature and moisture content). Therefore, frequent removal of poultry manure from housing will result in lower rates of ammonia emissions than from a deep-pit or deep litter system.

Farm energy consumption Increased running of automatic scrapers and tractor running a scraper or a vacuum pump will increase energy consumption. Belt removal systems for clearing manure from caged or tiered poultry housing will also increase the energy requirement.

Farm ammonia emissions Ammonia emissions from a dairy cubicle house derive predominantly from urine, following hydrolysis of the urea content to ammonium through action of the ubiquitous enzyme urease. More frequent removal of urine and faeces by scraping will increase the proportion of urine removed from the floor surface prior to hydrolysis and also leave a smaller ‘pool’ of material from which emission is occurring at any one time. A build up of faeces on the floor impedes the natural drainage of urine, so more frequent removal will also increase the volume of urine reaching the slurry store by natural drainage (particularly with a sloping floor), thereby reducing emission from the cubicle house. A reduction in ammonia emission from cubicle houses of 20% is estimated from such an increase in scraping frequency (to 4 times daily) (Braam et al., 1997). Further increases in scraping frequency may not greatly improve effectiveness, as scraping will leave a thin layer of emitting material across the entire floor area. Assuming a 10% current implementation, the maximum reduction which could be achieved by implementing this method in the UK dairy sector is about 1.5 kt NH3. Frequent removal of pig manure from below slatted-floor storage is estimated to give a 25% reduction in emissions from pig housing (based on the EC BREF document, European Commission, 2003), although more experimental evidence is required to


provide a robust reduction value. A key factor for the success of this method is that the slurry should be removed completely each time (twice per week), otherwise an emitting surface will still be present. Also, that ammonia emissions from outdoor slurry storage (generally under cooler conditions than within the house) are not further increased, which can be controlled by using a store cover. Ammonia emissions from laying hen houses with belt clean systems are approximately 50% less than those from deep-pit laying hen houses, based on UK measurements (WA0651, 2002; Nicholson et al., 2004). Part of this could be attributed to the higher temperatures inside the bird houses compared to outdoor storage.

Risk of water contamination incidents An increase in the readily available N content of the slurry at spreading will also increase the potential for pollution via other N losses (e.g. drainflow/surface run-off, nitrate leaching, nitrous oxide emission).

Animal health status More frequent removal of urine and faeces from cubicles passages is likely to improve the hoof health of cattle because manure has a detrimental affect on horn, leading to more heel horn erosions, and digital and interdigital dermatitis (Sogstad et al., 2005). 5.5. Use of manure on site of production as part of 'whole farm' approach While some farmers see manure as a waste that constitutes a problem that has to be coped with, it should really be viewed as a valuable resource that reduces the amount of mineral fertiliser that needs to be purchased and spread. Recycling nutrients from manures using a whole-farm approach can reduce a number of potential pollution problems (Petersen et al., 2007). There is much potential in the use of manures as fertiliser in mixed farming systems, or on closely neighbouring specialist crop and livestock farms (Wilkins, 2008). Using a recognised fertiliser recommendation system (e.g. RB209, PLANET, MANNER (MANure Nitrogen Evaluation Routine; www.adas.co.uk/manner; Chambers et al., 1999) and other supplementary guidance) allows the farmer to make full allowance of the nutrients applied in manures and reduce mineral fertiliser N inputs accordingly. Manure analysis provides a better understanding of the resources available, and robust recommendation systems can be used to provide a good estimate of the amount of nutrients supplied by manure applications. This information can then be used to determine the amount and ideal timing of additional mineral fertiliser required by the crop. The British Survey of Fertiliser Practice shows that farmers do not always fully allow for the nutrients in applied manure when calculating mineral fertiliser rates. In most cases, making proper allowance for the nutrients in manures will result in a reduction in mineral fertiliser inputs compared with current practice and a concomitant reduction in NO3 losses.

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Manures can be analysed by a commercial laboratory (e.g. for total N and for NH3-N). Alternatively, quick on-farm tests such as the Agros Nitrogen Meter (http://agros.se/engelska.html), Quantofix N meter (Klasse and Werner, 1987) and the Reflectoquant meter (available from Merck) can give reasonably accurate values (Kessel and Reeves, 2000; Reeves et al., 2002). The amount of N is reduced at source. Mineral fertiliser applications are reduced to no more than is required for optimum economic production levels. Excess N in the soil is reduced. When slurry is spread too soon after the application of N fertilisers, there is a risk of increased N2O emissions through the process of denitrification. Current advice is to leave at least 5 days between applications of slurry and mineral N fertiliser to the same field to allow readily decomposable sources of carbon to be degraded (Stevens and Laughlin, 2002; Dittert et al., 2005).

Farm energy consumption Use of manure on-site reduces the energy required to move it and therefore minimises transport fuel costs.

Farm ammonia emissions There may be an additional benefit in reducing NH3 emissions if manures are more rapidly incorporated into arable land (Defra projects ES0115 and ES0116) or slurries are applied using shallow injection or trailing shoe/hose equipment rather than being broadcast on the soil surface (Defra projects ES0114 and ES0115).

Farm greenhouse gas emissions Use of manure N to its full potential would reduce mineral N fertiliser use, and therefore a reduction of N2O emissions would be expected. The value of this reduction would depend on the reduction in mineral N fertiliser, and the quantity of manure N supply, which we estimate to be around 5% (Cuttle et al., 2007).

Risk of water contamination incidents Cuttle et al. (2007) concluded that this mitigation method could reduce NO3 leaching from arable land and dairy grassland by about 5% through reduced mineral fertiliser N applications. This assumed no change in the timing of manure applications.

Animal health status Using manures on the farm from which they originate, or on neighbouring arable farms with no livestock present, helps biosecurity by minimising the risk of spread of disease. 5.6. Active nutrient management planning Actively managing the nutrient flows within a farming system, which may be greater than a single farm, is consistent with maximising the economic return of the enterprise and minimising the nutrient losses from, and pollution risks associated with, the whole system (Beegle et al., 2000). An example of this is the use of outdoor pigs as part of an arable rotation, which may occur on a single farm enterprise, or as part of a rotation involving land rented from neighbouring arable farms.

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For livestock systems involving crop production or grazing, a nutrient management plan should include regular soil analyses to ensure that soil pH, N, K, P and Mg indices are optimised for the crops/pastures grown (Pierzynski and Gehl, 2005), and that excess nutrients are not applied, leading to surpluses that are more likely to be lost as pollutants (Berry et al., 2003; Cole et al., 2005b). Manure analyses should be obtained so that nutrient supplies available from them can be taken into account when assessing soil nutrient requirements (Powers and Van Horn, 2001). The Fertiliser Advisers Certification & Training Scheme (FACTS; www.factsinfo.org.uk) is a nationally validated non-statutory scheme developed by the fertiliser industry as a form of self-regulation. It was set up in response to an E.U. investigation into the standards of competence of those advising on fertiliser use. Wherever possible, farmers should obtain nutrient management advise from FACTS certified advisors.

Farm ammonia emissions A large proportion (up to 38%) of N excreted in livestock housing can be lost as NH3 during storage and applications to land (Oenema et al., 2007). Planned mitigation options (discussed elsewhere) to reduce emissions mean an increased capture of excreted N and reduced fertiliser requirements.

Farm greenhouse gas emissions Active management of fertiliser-nutrients, ensuring that appropriate quantities are applied at appropriate times, can significantly help to reduce N2O emissions (Moorby et al., 2007; van der Meer, 2008).

Risk of water contamination incidents Ensuring that soils are not overloaded with excess manure or chemical fertiliser nutrients can reduce nutrient leaching and pollution incidents. Increased risk of water pollution incidents has been identified in areas with very high livestock densities (Lord et al., 2002), thereby indicating the need for livestock producers to carefully manage manure and fertiliser resources.

Consistency with legal requirements Farms operating within a Nitrate Vulnerable Zone are legally obliged to plan and keep records of N applied to individual fields in the form of manures, fertilisers or other N-containing materials in addition to the requirements of crops (including grass) in those fields.

Integrated farming methods Active use of a nutrient management plan is central to an integrated approach to farming.

On-farm use of chemicals Actively managing nutrients at both the whole-farm level and also at the individual field level can reduce chemical fertiliser inputs, and therefore fertiliser costs.


5.7. Spread manures to land in compliance with a Manure Management Plan A good manure management plan is an integral component of Good Agricultural Practice, and is essential for enterprises within an NVZ. Guidelines for drawing up a manure management plan can be found at: http://www.defra.gov.uk/corporate/docs/forms/agri_env/nvz/manureplan.pdf Key components of a manure management plan include knowledge of restricted areas (e.g. water courses), soil types, manure nutrient contents, crops used in the land on which the manure will be spread, and manure quantities. 5.8. Time manure / slurry applications to land to maximise fertiliser value

and minimise pollution Cattle slurry has a high content of readily-available N compared to (straw-based) farmyard manure, which has a relatively low content of readily-available N. Applications of slurry in particular should be made when there is crop demand for N, otherwise there is an increased risk of losses through direct soil emissions and leaching. Therefore, applications in autumn and early winter should be avoided (with the possible exception of light applications of slurry to autumn-sown oil seed rape crops, which respond to small amounts of manure-N application; Defra project WQ0118), and shortly before or after heavy rainfall (risking water-logged soils) or when the ground is frozen. Applications later in winter present less of a risk, as low temperatures slow the rate of conversion of ammonium to NO3 and there is less opportunity for direct N2O losses (Moorby et al., 2007). This will only be applicable on farms that have sufficient storage capacity to allow a choice of when to apply slurry. The use of covered slurry stores (Section 5.14) can help by reducing the volume of slurry that needs to be stored by preventing dilution by rain water, providing the farmer greater flexibility in the timing of slurry applications. On many indoor pig and poultry farms, land applications have to coincide with clean-out times or rely on field heaps as buffer stores. This is particularly the case for poultry meat sites although many large cage egg production sites have covered manure storage facilities that allow more flexibility. Larger poultry sites normally also have containment facilities for dirty water. Even where storage is adequate for normal conditions, exceptional weather or poor planning can create a situation where stores are full during a high-risk period so that land spreading is the only option. It would generally be acceptable to apply slurry to grass later in the season than for other crops, as long as the sward continues to take up N (i.e. when it is still growing).

Farm ammonia emissions There are likely to be greater NH3 emissions from spring slurry applications to arable land and following summer applications to grassland, which were estimated to be in the range 10-20% depending on the increased proportion of slurry applied in spring/summer (Defra project WT0706).

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Farm greenhouse gas emissions High-risk times for direct N2O losses will be most frequent in high rainfall areas and on soils with a high clay content (Defra projects CC0241 and CC0251). Indirect N2O losses will be greater on shallow or sandy soils and on artificially drained soils where there are preferential loss pathways. There are also likely to be small increases in CH4 emissions from the increased period of slurry storage and small increases in NH3 emissions because of the increase in slurry store surface area, as a result of the greater amount of slurry storage capacity needed to facilitate these changes in application timing.

Risk of water contamination incidents Spreading straw-based farmyard manure at high risk times increasing the risk of N, P and pathogen transport to water courses in run-off water. Fresh farmyard manure has higher concentrations of available N and faecal pathogens, and therefore storage prior to spreading helps to minimise risks of contamination by these (Cuttle et al., 2007). Defra project WQ0118 is currently in progress to determine the potential of rapid-flow pathways in cracking clay soils (i.e. those which develop deep cracks in dry conditions) to increase the speed with which potential contaminants (from manure and fertiliser applications) can reach ground water and leach into watercourses. Consistency with legal requirements Closed periods for spreading high N slurries in NVZ’s ensure reduced risk of winter applications with increased risk of losses through direct soil emissions and leaching. 5.9. Methods of manure application to land: broadcast on land, no

incorporation In general, rates of emission of ammonia, odours and GHG are higher from manures broadcast directly onto land, with no incorporation, compared to practices that rapidly incorporate the manure into the soil. Practical measures for doing this include cultivation (ploughing or disking) or the use of slurry injection systems. See Section 5.10. 5.10. Methods of manure application to land: rapid incorporation

Farm ammonia emissions Incorporating broadcast manure into the soil (e.g. by ploughing or with disc or tine cultivation) greatly reduces the exposed manure surface. Diffusion of any ammonia present within the soil pore spaces to the surface is much slower than emission directly from the soil surface. The ‘free’ ammonium content of the slurry placed within the soil will also be reduced through direct adsorption to clay particles and through the action of nitrifying bacteria, further reducing the potential for ammonia emission. Ammonia emissions can be reduced by up to 90% compared to emissions from manures left on the soil surface (Webb et al., 2004; Misselbrook et al., 2008; Mkhabela et al., 2008).


This is particularly applicable to manure applications to arable land prior to crop establishment. The method could also be applied to grassland reseeds.

Farm greenhouse gas emissions Reducing ammonia emissions from the applied manure increases the potential for nitrogen losses via nitrous oxide emissions, depending on the manure type (risks are greater for slurries than solid manures), time and rate of application, although N2O emissions can also be reduced (Webb et al., 2004). Reduce odour and nuisance Rapid incorporation is likely to reduce odour emissions during slurry spreading operations.

Risk of water contamination incidents Rapid incorporation of manure into the soil will also reduce the risk of mobilisation of manure nutrients and pathogens in surface run-off waters (Cuttle et al., 2007). Reducing ammonia emissions from the applied manure also increases the potential for nitrogen losses via nitrate leaching. When manures are incorporated, microbial pathogens are protected from ultra-violet radiation and may survive for longer in the soil. However, as they are mixed throughout the soil matrix, they are less likely to be lost in surface run-off and via drain flow. 5.11. Use of mechanical separation of manures and slurries Nitrogen is predominately excreted by mammals in urine in the form of urea. Nitrification of this to ammonia occurs through the action of urease, from microbes in the soil and also in faeces. Immediate mechanical separation of urine and faeces reduces the contact between urea in urine and urease in faeces. This can be achieved through the design of flooring to allow drainage and separate storage of urine and faeces, or through belt separation (see Ndegwa et al., 2008, for a review). Pre-storage separation of manure liquids and solids can substantially increase the quality (cleanliness) of effluent stored in a slurry lagoon (Vanotti and Szogi, 2008). Some pig farms and some dairy farms use mechanical separators. The liquid fraction of the separated manure is suitable for pumped irrigation, while the solid fraction can be composted and used as a solid fertiliser. The digested output of an anaerobic digester can also be separated and the fractions used likewise (Cantrell et al., 2008).

Farm energy consumption As well as having a high capital outlay cost, mechanical separators use electricity and therefore have a high running cost.

Farm ammonia emissions Mechanical separation of manure solids and liquids can increase net ammonia emissions compared with untreated manures (Amon et al., 2006), largely as a result of composting the solids fraction (Hansen et al., 2006). The scale of emissions depends on the source of manure, with higher emissions of NH3-N from pig manure


than from cattle manure (Petersen et al., 1998). Covering composting manure solids heaps with an impermeable cover (i.e. plastic) can significantly reduce NH3 and other volatile emissions (Hansen et al., 2006).

Farm greenhouse gas emissions Removal of liquid from manures by separation can increase the volatile solids fraction of manure, improving methane yield when this is then digested in an anaerobic digester (Møller et al., 2004). The yields of methane from the separated manures depends on the animals species, the diet they are fed on, and the method used for separation (Møller et al., 2007). 5.12. Capture of dirty water in covered stores Dirty water is generally defined as water collected from buildings, yards and milking parlours that is contaminated with slurry, i.e. is very dilute slurry. To avoid pollution of water courses it needs to be handled appropriately, which usually means capture and storage for disposal by irrigation to land. However, the addition of dirty water to slurry stores reduces the capacity for slurry storage and lowers the dry matter content of the slurry. Therefore, capture of dirty water into a separate storage facility, although involving significant economic investment, is the best method of handling it.

Farm ammonia emissions Webb et al. (2001) highlighted the important contribution of concrete yards to NH3 emissions from UK livestock farms, and how this can be reduced by hosing them down regularly. However, they estimated that this would increase the quantities of dirty water produced by 20%, requiring storage, and potentially covered storage (particularly for large pig units). Covering dirty water storage is likely to reduce NH3 emissions from dirty water containing slurry as is the case for slurry stores (Section 5.14).

Risk of water contamination incidents Dirty water on dairy farms can include slurry from yards and milking parlour washings and effluent from silage and manure storage areas (Brewer et al., 1999). Covering above-ground storage tanks or lagoons reduces the ingress of rainwater, thereby reducing the amount of dirty water that needs to be disposed of, effectively extending the slurry storage capacity. On poultry sites, dirty water arises from wet cleaning of buildings after depopulation. Dirty water is usually directed to an underground storage tank. 5.13. Capture of dirty water in un-covered stores As discussed in Section 5.11, separate storage of dirty water reduces the storage requirement of slurry. Uncovered dirty water storage are more typically found on smaller enterprises. Storage tanks with no covers allows the ingress of rain water, which dilutes the dirty water concentration and increases its volume. This decreases the potential storage capacity of tanks and increases the amount of dirty water that must be disposed of. This has implications for livestock farmers in NVZ’s who must


provide, by 1 January 2012, at least six months’ storage capacity for poultry manures and pig slurry, and at least five months’ storage capacity for slurry from other types of livestock. 5.14. Use of covered slurry stores

Farm ammonia emissions Ammonia will freely volatilise from a slurry store surface (the rate depending on factors such as ammonium-N concentration, pH, temperature and air movement), and will be replenished in the surface layer from lower levels in the store. Natural air movement above the store (i.e. wind) ensures that the emitted ammonia is removed from above the store, being continually replaced by air with a lower ammonia concentration. By placing a cover above the slurry surface and preventing the removal of emitted ammonia by advection, a higher ammonia concentration will soon develop in the enclosed airspace. This higher concentration will inhibit further ammonia emission from the slurry, so the overall emission rate will decline. Most covers include some vents (to prevent a build up of methane), so emission will not stop entirely, but will be greatly reduced compared with a situation of free air movement above the slurry store (Misselbrook et al., 2008). There may be little benefit in applying the method to cattle slurry stores, where natural crusts often develop and give effective ammonia emission reduction. However, natural crusts are lost when slurry is stirred frequently, and therefore a cover would be of benefit in this circumstance. The use of oil in slurry pits under slats in weaner pig housing can reduce NH3 emission by about 50% (Pahl et al., 2002). Also, little benefit will be gained from covering of very dilute slurry stores, so separate storage of slurry and dirty water is recommended with the slurry store being covered. The two waste streams may be brought back together at spreading if that suits the farm-specific manure management system. A rigid store cover has been shown to reduce emissions from slurry storage by 80%, plastic sheeting cover by 60% and ‘low technology’ floating covers by 40% (Sommer et al., 1993; Scotford and Williams, 2001; Portejoie et al., 2003). Implementing this method in the UK pig sector, with rigid covers fitted to tanks and plastic sheeting to lagoons, would give a reduction in emissions of 1.6 kt NH3 (AM0102, 2005).

Farm odour & nuisance emissions A cover will significantly reduce odours arising from slurry storage.

Risk of water contamination incidents Reducing ammonia emissions from slurry storage will result in a greater readily available N content of the slurry being applied to land, and will therefore result in a small increase in the potential for N losses following application (i.e. ammonia and nitrous oxide emissions to air, N in surface run-off/drainflow and nitrate leaching).


5.15. Integral store and cover (bag) Slurry bags have essentially the same benefits to the use of a cover on a conventional slurry store (Section 5.14). 5.16. Use of aerators for slurry systems Under normal circumstances, the activity of microbes in manures and slurries removes oxygen and they become anaerobic. Fermentation can then occur with the production of CO2 and methane as end products. Aeration of slurries maintains an aerobic environment, enabling respiration by aerobic microbes, with the formation of CO2, water and heat. Thermophilic aeration increases the temperature of the slurry (in the range of 45 to 70°C) with the effect of reducing the number of pathogenic microbes (Mohaibes and Heinonen-Tanski, 2004). Mohaibes and Heinonen-Tanski (2004) list the following advantages and disadvantages of thermophilic aerobic treatment of livestock slurries as: Advantages Disadvantages Simple, effective method of destroying pathogens

High energy requirements

Self-heating, heat recovery possible Aerosols in vented air Medium capital investment required Risk of emissions of NH3 and N2O Improves slurry characteristics Regular maintenance required Deals with a range of environmental problems

Complete treatment of slurry at high temperatures is energy intensive

Can be highly controlled and reliable Slow process, although faster than anaerobic treatments of slurry

Conversion of organic wastes into valuable end products

Foam production can be a problem

Air supplies are relatively cheap

Farm energy consumption Although electrical energy is required for the pumps needed to aerate slurries, the energy input is less than the heat generated (Heinonen-Tanski et al., 2005).

Farm ammonia emissions Although pumping air through slurry can increase the risk of volatilisation of ammonia, slurry can be aerated with little loss of NH3 (Skjelhaugen and Donantoni, 1998).

Farm greenhouse gas emissions Aeration of slurries can reduce the amount of methane produced. The amount of energy in methane generated from a slurry under anaerobic conditions is roughly equivalent to the amount of energy generated as heat under aerobic conditions (Heinonen-Tanski et al., 2005).


Farm odour & nuisance emissions Aeration can reduce the odour released from slurries, compared with normal un-aerated slurry (Skjelhaugen and Donantoni, 1998). 5.17. Use of nitrification inhibitors Nitrification inhibitors are chemicals that reduce the rate of conversion of NH4 to NO3. The rationale is that the rate of nitrification is reduced so that NO3 is formed at a rate that the crop can use (i.e. slow release), increasing N efficiency and reducing environmental losses via N2O emissions and NO3 leaching. Compounds such as nitrapyrin, dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) have been demonstrated to be effective in reducing N2O emissions from fertiliser and animal slurries. Chemicals such as DCD have been evaluated for reducing N losses from autumn applied slurries for many years, but have generally failed to gain acceptance with the farming community due to their poor cost-effectiveness in terms of giving yield benefits and reduced NO3 leaching losses (Chambers et al., 2000). However, Dittert et al. (2001) showed that inhibitors reduced N2O emissions by about 30% when they were mixed with slurry and injected into grassland in late summer. More recent research conducted in New Zealand, has shown that nitrification inhibitors can be extremely effective (depending on soil type) when added to mineral fertiliser, manures and even dosed to animals in reducing N2O emissions. In the laboratory, such inhibition has been shown to be potentially close to 100% efficient, while reducing to about 30% typically under field conditions (Hatch et al., 2005). Nitrification inhibitors are currently expensive and this may reduce the uptake of their use by farmers, but the reduction in mineral fertiliser requirements through reduced N losses may offset this cost.

Farm ammonia emissions Reducing the rate of conversion of NH3 to NO3 increases the risk of N losses as NH3 through volatilisation (Prakasa Rao and Puttanna, 1987; Davies and Williams, 1995). These losses can be reduced by the methods of fertiliser application (e.g. by placing urea fertiliser below the soil surface; Prakasa Rao and Puttanna, 1987), although this may not always be practical.

Farm greenhouse gas emissions Recent research in New Zealand (www.ravensdown.co.nz/products/ national2005/specialist.html and www.ballance.co.nz/unewsapr07-05.html) points to high potential effectiveness. Ravensdown claim a 7-15% yield response rate to use and Ballance AgriNutrients suggest that nitrification inhibitor use can reduce NO3 leaching losses by up to 35%. However, New Zealand grazing paddocks, which are generally on free draining and have a long growing season, are very different to the UK situation (where soils are predominantly heavy textured and the growing season is much shorter).

Water quality Although the evidence is unclear at this time, New Zealand research suggests that NO3 leaching losses should also be reduced by using nitrification inhibitors.


5.18. Use of urease inhibitors Urease inhibitors reduce the hydrolysis of urea to NH3, by bacterial ureases, and thus reduce the rate of volatilisation losses when urea is used as a fertiliser. Reducing the rate of hydrolysis enables urea applied as a fertiliser, or when supplied in manures, to better penetrate the soil surface and therefore reduces the losses of NH3 to air once it is eventually formed (Watson, 2000). The most widely used urease inhibitor is N-(n-butyl) thiophosphoric triamide (NBPT), which is marketed under the trade name Agrotain. As with nitrification inhibitors, the increased cost of using a urease inhibitor with applications of urea fertiliser may be offset by a reduction in application requirements.

Farm ammonia emissions The effectiveness of urease inhibitors at reducing NH3 losses from urea-based fertilisers depends on the soil type, ambient temperature, soil water content, rate of inhibitor use, and fertiliser/inhibitor formulation (Defra project NT2605). With rates of application of NBPT with urea of around 0.1% weight/weight, reductions of between 28 to 88% (and up to 96% are peak rates of standard urea losses) have been found (Rawluk et al., 2001). 5.19. Account taken of land/receptor/weather considerations regarding

application practices All responsible farm businesses aim to achieve this, being consistent with Good Agricultural Practice to minimise odour nuisance and pollution risks, although it is not always possible due to rapid or unexpected changes in the weather.

Farm ammonia emissions Rainfall, following spreading of manure to land, dilutes NH3 concentrations and can therefore reduce NH3 emission rates following spreading. However, this effect is only temporary and NH3 emissions will increase again once rainwater evaporates (Sommer and Hutchings, 2001), although this delay can be beneficial if it allows manures to be incorporated into land by field operations.

Farm greenhouse gas emissions Nitrification of NH3 (e.g. from urea in urine) to nitrite is an oxidation processes. The denitrification process, on the other hand, is carried out principally by anaerobic microbes, and therefore the emission of N2O from soils is related to their water-filled pore space, or moisture content (e.g. Bedard-Haughn et al., 2006). Rainfall events can therefore drive N2O emissions from recently fertilised soils (Li et al., 1992). 5.20. Account taken of cross compliance, including local restrictions e.g. NVZ Cross compliance requirements are the activities that must be undertaken by farmers if they are receiving payments under Common Agricultural Policy (CAP) support schemes, e.g. the Single Payment Scheme (www.crosscompliance.org.uk). These currently include Statutory Management Requirements (SMRs) and legal requirements to keep land in Good Agricultural and Environmental Condition (GEAC). It is notable that in a survey of farmers designed to assess the perception


of environmental legislation (i.e. Nitrate Vulnerable Zones; NVZ), most were concerned only with on-farm issues, and none felt responsible for negative environmental impacts of their farming activities either on- or off-farm (Macgregor and Warren, 2006).

Water quality One example of cross compliance is the EU Nitrates Directive (Directive 91/676/EEC), which has led to the designation of NVZ covering 68% of the total area of England, 14% of Scotland and 4% of Wales. In these areas key measures to limit the application of N to land are as follows:

• A limit of 170 kg N/ha per year of livestock manure N that is produced on the farm, allowing for livestock manure N that is moved onto the farm or taken off the farm. Note: The governments of Britain (i.e. England, Scotland and Wales) are presently applying for a derogation from the 170kg N/ha per year livestock manure N loading rate limit.

• A minimum storage capacity requirement of 6 months for pig slurry and poultry manure, and 5 months for all other livestock manures. New or modified stores must meet the appropriate construction standards. Controls on the temporary storage of solid manures in field heaps.

• A requirement to plan the applications of all nitrogen fertilisers for each crop in each year, before any nitrogen is applied.

• A limit on the rate of nitrogen fertilisers that may be applied to individual crops, for example 300 kg N/ha on grassland, 220 kg N/ha on autumn/early winter sown wheat (standard yield 8 t/ha) and 250 kg N/ha on winter sown oilseed rape (standard yield 3.5 t/ha). The contribution of crop available manure N to the limit must be calculated using the following mandatory values for the manure N coefficient (% of total N applied): o cattle slurry 35% o pig slurry 45% o poultry manure 30%

• There are closed periods during the autumn and winter on all soil types for the spreading of high readily available organic manures to land, ranging from 3 to 5 months depending on the soil type and cropping. There is also a closed period for the spreading of chemical nitrogen fertiliser to land.

• Controls on where nitrogen fertilisers may be applied, including a requirement to produce a farm-level risk map showing areas that are suitable for spreading manures and for storing solid manures in field heaps.

• Controls on how nitrogen fertilisers are applied so that nitrogen fertiliser or nitrogen-enriched surface run-off does not reach surface waters.

• A requirement to keep specific records for at least 5 years. • Improvements in the N utilisation efficiency of livestock.


5.21. Use of anaerobic digesters for manure

Renewable energy Methane produced from slurries and manures has valuable potential to replace fossil fuel use. Processing in digesters that capture the CH4 for burning enables this energy to be used and at the same time reduces the global warming potential of the gas released into the atmosphere (CO2 instead of CH4). To increase CH4 yield, food ‘wastes’ are commonly added to the digestion process. Additionally, the food ‘wastes’ provide a valuable source of income via gate-fees. Anaerobic digestion (AD) of organic materials (manures plus potentially other wastes) by microbial populations in a sealed container results in the formation of CH4 and digestate. Methane produced by these processes can be used for heating and power (e.g. Jiang et al., 1987), and the digestate returned to the land as a soil conditioner and fertiliser.

Farm ammonia emissions During AD, organic N is mineralised to ammonium (NH4

+) N. Furthermore, N can be added by the inclusion of other (e.g. food ‘waste’) materials. Hence, the N content of the digestate can be greater than that of the original ’raw’ manure. This could potentially result in greater NH3 (during both storage and following land spreading) and N2O emissions, and NO3 leaching losses following land spreading (depending upon application timing).

Farm greenhouse gas emissions Methane emissions from slurry storage would be significantly reduced (estimated at up to 90%) by this method compared with conventional slurry storage. Plus there would be additional energy produced that would replace fossil fuel use. Other GHG emissions would most likely not be directly affected (Moorby et al., 2007). As above, there is potential for increased N2O emissions following land spreading of AD digestate. There is potential for diverting food ‘waste’ materials away from landfill so leading to a reduction in methane production.

Farm odour & nuisance emissions There is potential to reduce the emissions of odours from cattle farms through the use of AD (Powers et al., 1999).


6. Housing and Environmental Control

List of practices considered most important in the area of housing and environmental control and considered in this section. 6.1 Bedding type 6.2 Mobile versus static housing for outdoor access systems 6.3 Use of stand-off pads 6.4 Use of lower stocking density systems 6.5 Use of existing and 'traditional' farm buildings for multiple uses 6.6 Environment controlled to optimise production 6.7 Use of powered ventilation systems 6.8 Use of natural ventilation systems 6.9 Ventilation requirements efficiently delivered - optimum fan performance 6.10 Use of renewable energy sources 6.11 Use of heat recovery systems 6.12 Use of sprinkling or misting systems 6.13 Use of energy-efficient or natural light sources 6.14 Use of light dimmers and timers to save power 6.15 Use of systems that allow animal free choice 6.16 Use only of dry-clean methods for house cleaning 6.17 Use of recycled water for house cleaning 6.18 Optimal use of chemicals during clean-out 6.19 Use of detergents/degreasers at clean-out 6.1. Bedding type A wide range of bedding systems and types is used in livestock housing. Cattle systems range from individual cubicles with a range of coverings and bedding, to concrete floors with slats and no bedding. Where pigs are kept on litter systems (as opposed to slats), straw is generally used. Barley-straw is favoured by many outdoor pig keepers to provide a softer form of bedding than wheat straw. Poultry kept for meat production are kept on all litter-floored systems, whilst laying hens kept in non-cage systems have access to litter as well as slatted floor areas. The choice of bedding used by a farmer for a particular livestock species depends on housing infrastructure, machinery availability, cost, and animal management system. Compliance with high-welfare pig production contracts will also be a key driving factor when choosing straw, for example. Price and availability are not the only factors to take into account – welfare, comfort, safety, absorbency and practicality must also be considered. Straw is very commonly used, particularly for loose housed cattle, sheep, pigs, turkeys and ducks. Straw may also be a constituent of litters for chickens although wood shavings are commonly used. Variability in the quality of straw can be an important issue. Some alternatives to straw include: Wood shavings and coarse sawdust. These can be a very absorbent and clean bedding but must be sourced from seasoned or clean recycled timber or be kiln-dried to have a low moisture content. Wood shavings are commonly used for poultry and for cattle in cubicles as they are typically less labour-intensive than straw. Wood


shavings are compatible with most slurry systems and do not cling to the animals, making preparation for market easier than some other bedding types used for large animals. Dust-extracted wood shaving and sawdust are most appropriate to reduce dusty housing conditions. Paper. This is most commonly used for bedding dairy cubicles but is equally useful for lambing sheep, can be used for farrowing sows to fulfil nest-building behaviour and can be used for poultry in a pelleted form. It has a very high dry matter content, making it extremely absorbent, and is very clean and hygienic. It is best used under straw or sawdust to prolong its life and reduce straw use. Any wetness is wicked down and the straw stays dry. It must be stored indoors, and once used it can be spread straight on to land and is suitable for all types of slurry system. Shredded, pulped or chopped paper is another alternative, however, it can set hard once wet, so can be difficult to muck out and spread effectively. Sand. This is a clean, dry bedding suitable for loose or cubicle housing. Sand is abrasive on machinery, and not suitable for some slurry systems. It can also cause problems at abattoirs, where it blunts knives easily. Woodchip. This can be used effectively as indoor bedding for sheep and cattle, or outdoors on stand-off pads. Woodchip is especially useful for farms with a cheap supply of timber. After use, the woodchip bedding must be composted and regularly turned to encourage high temperatures that kill pathogens. Woodchip compost is not suitable as a soil conditioner/fertilizer until it is fully broken down and this may take 2-3 years. During that time, woodchip sanitised by composting can be re-used as bedding. The addition of lime to bedding can reduce bacterial counts on it (Hogan and Smith, 1997) and can be better at reducing bacterial counts in sawdust than daily replacement.

Farm ammonia emissions The use of straw as a bedding material for housed cattle, so that excreta are collected as solid farmyard manure compared rather than as liquid slurry, can reduce the potential for ammonia emissions (Misselbrook et al., 2008). Ammonia emissions from systems using sawdust may be lower than those from systems using straw or chopped newspaper (Powell et al., 2008). For poultry systems, emphasis is placed on keeping litters dry and friable so that ammonia emissions are minimised.

Farm greenhouse gas emissions Using a slurry-based manure system maintains excreta in a more anaerobic environment, and therefore reduces the conversion of ammonia to N2O. Therefore, N2O emissions tend to be lower from slurry systems than straw-based systems, at least from livestock housing and manure stores (Moorby et al., 2007). On the other hand, reducing litter density during composting of pig manure by incorporating straw could reduce CH4 and N2O emissions from the heap (Sommer and Møller, 2000).


Farm dust emissions Choice of bedding materials, and the way in which they are prepared, spread and removed from animal housing can have significant effects on levels of dust. In turn, this can affect the health of both animals and people working in the housing. As well as presenting physical and allergenic challenges to animals and humans, dust particles can carry pathogens (Bakutis et al., 2004), and bedding dust and other allergens can be carried from the animal housing to worker housing (Berger et al., 2005). In poultry systems, the need to maintain litter in a dry condition in order to control ammonia and safeguard welfare can increase dust emissions.

Use of recycled materials Paper and cardboard bedding products are typically derived from newspaper and other recycled paper-based products.

Animal welfare standards Bedding has clear benefits in terms of preventing physical damage to livestock, compared with bare (solid or slatted) concrete or wooden floors in housing (e.g. Ingvartsen, 1993; Gordon and Cockram, 1995; Andersen and Boe, 1999; Tuyttens, 2005). However, poor quality litter can be a significant factor in the incidence of welfare problems such as pododermatitis and hock burn in chickens. Bedding type can have significant effects on the foot health of poultry, with chopped straw apparently the least suitable among a range of bedding types (Berk, 2009), and wood shavings being a better alternative (Meluzzi et al., 2008a). Maintaining good quality litter is a function of good stockmanship allied to suitable housing, nutrition and appropriate stocking rates. For bedding cattle cubicles with sawdust, cow comfort is improved by using thicker bedding compared with minimal or no bedding (Tucker and Weary, 2004). However, although the use of large amounts of litter may aid animal welfare, they increase resource use and transport costs. Much work has been done to investigate the potential environmental enrichment benefits of using straw and other bedding types for pigs (Arey, 1993; Whittaker et al., 1999; Tuyttens, 2005; van de Weerd and Day, 2009) and poultry (Shields et al., 2004; Shields et al., 2005). Bedding can help reduce boredom in animals compared to a bare environment, although the presentation of that bedding (e.g. chopped versus unchopped straw) can also influence behaviour (Day et al., 2008).

Protection against animal disease impact Bedding choice (e.g. sawdust or sand in cow cubicles) can influence the prevalence of pathogens from faeces (LeJeune and Kauffman, 2005). The relationship between animal (pigs and cattle) health and straw as a bedding material is complicated (Tuyttens, 2005). The use of good quality straw is important – very dusty straw, or straw infected with mycotoxins can have serious effects on animal and worker health and can adversely affect livestock performance. 6.2.


Mobile versus static housing for outdoor access systems Mobile housing is used by some small-scale poultry producers for free range flocks, but larger sites generally prefer fixed buildings. Mobile houses are typically used in outdoor pig production but the degree of mobility varies with the size of structure. Vehicles are normally required to move mobile structures, and thus movement of houses in wet conditions can be difficult, particularly in fields that have been heavily turned over by rooting pigs. Smaller, mobile structures are more prone to damage during windy weather compared to static structures. Sheep and cattle housing is typically not mobile.

Risk of water contamination incidents Regular movement of outdoor pig shelters can help distribute excreted nutrients more evenly across paddocks (Eriksen et al., 2006), thereby reducing their concentrations in particular areas and reducing the chance of leaching through excessive loading. The same principle applies to poultry systems.

Animal welfare standards The freedom to choose between outdoor and sheltered environments is a major benefit to free-range pig and poultry systems. However, potentially increased contact with infectious agents, greater difficulty in maintaining good hygiene, and the threat of predation balance this. Mobile poultry housing systems are generally smaller in scale to static systems, potentially enabling easier maintenance of hygiene (through rotation/housing movement) and improved animal welfare through reduced flock sizes (Knierim, 2006).

Protection against animal disease impact The use of mobile housing in outdoor systems can help maintain a clean and hygienic environment by offering greater scope for paddock rotation. This reduces parasite build-up in the soil, allows maintenance of ground cover vegetation, and enables easier integration with other farming enterprises. Acceptability to customers Mobile systems may meet customers’ expectations in terms of the nature of the system, flock size etc, but the additional costs incurred on the farm will make the final product more expensive and possibly less affordable to some. Rural employment Mobile systems tend to be more labour intensive partly because of the additional task of moving the houses periodically but also because they tend to be more widely distributed with lower levels of mechanisation and automation. Integrated farming methods Pig and poultry systems that are based on moveable houses are easier to integrate with other farming enterprises, with manure depositions acting as a fertiliser for subsequent crops. 6.3.


Use of stand-off pads Cattle may be out-wintered on purpose-built woodchip stand-off pads as an alternative to winter housing. The stand-off pads ideally incorporate an impermeable liner and drainage collection system to collect slurry run-off.

Farm ammonia emissions Ammonia emissions from urine deposition on a woodchip stand-off pad are likely to be substantially lower than those on a concrete yard or within a cattle house, because of rapid infiltration into the woodchip matrix. This greatly increases the physical barrier to volatilisation of ammonia, in a similar way to bedding material in livestock housing and soil when cattle are at grazing. There may also be some direct adsorption of ammonia to the woodchip media and potential for microbial immobilisation from the development of a bacterial community within the media. Additionally, drainage from the stand-off pad will lower in N content and dry matter when compared with cattle slurry from housing, and so the potential for ammonia emissions following application is likely to be lower than for housed systems, because of more rapid infiltration of the lower dry matter/N content material into the soil (Smith et al., 2005).

Risk of water contamination incidents Providing that the stand-off pad is lined and drainage is collected (McDonald et al., 2008), there is no increased risk of water pollution when compared with conventional housing systems.

Animal health status Use of stand-off pads for over-wintering dry cows had no deleterious effects on animal health in terms of lameness or locomotion scores (O'Driscoll et al., 2008a), and cows were less prone to limb lesions compared to those housed in conventional free-stalls (O'Driscoll et al., 2009). Despite this, cows hooves were softer when out-wintered on stand-off pads (O'Driscoll et al., 2008a; O'Driscoll et al., 2009), with slightly higher incidence of hoof lesions. This was mitigated by the use of covered pads. Dry cows out-wintered on covered stand-off pads were cleaner, and tended to have lower somatic cell counts in the subsequent lactation compared to dry cows out-wintered on uncovered stand-off pads (O'Driscoll et al., 2008b).

Sustainable management of land During wet conditions when cows have to be removed from grazing paddocks to protect the pasture and soil, stand-off pads are a good alternative to using ‘sacrifice’ paddocks. The soil is likely to be less poached and therefore animals are likely to become less muddy (Fisher et al., 2003). 6.4. Use of lower stocking density systems Lower stocking density systems mainly relate to ‘extensive’ production methods and to farm assurance schemes, such Freedom Food and organic standards.


Animal welfare standards A lower stocking density means animals have more space to move about in and more opportunity to exhibit natural behaviours. In some cases, there may be potentially easier access to feed and water supplies, and feed consumption together with the quantity of bedding necessary may increase. However, more housing space is needed in total (a lower stock carrying capacity will apply to a given farm size), which could impact on the visual appearance of farms. With fewer stock in a given indoor area, there is more scope for reliance on natural ventilation systems. Lower stocking densities in livestock housing can result in lower ambient temperatures and unless a minimum ventilation rate is set, humidity and ammonia will accumulate. Slotted roofs in cattle housing (with gaps between roofing sheets) rely on a high stocking density to generate heat that causes stale air to rise and escape. At low stocking densities insufficient warm air circulation can lead to the ingress of rain through the roof. In broiler houses, reduced stocking density does not necessarily improve bird welfare: Meluzzi et al. (2008b) found no clear relationship between stocking density and mortality rate. During temperature extremes, there is a tendency for pigs to reverse their dunging habits and for litter condition to be adversely affected, although welfare of the pig is enhanced through the pig being able to maintain it’s body temperature.

Protection against animal disease impact Lower stocking densities can mean less competition between animals and improved health parameters. For example, reduced stocking density of broiler chickens was found to lead to improved foot health (Meluzzi et al., 2008a).

Effect on livestock output or performance For grazing dairy cattle, lower stock densities tend to lead to less than optimal rates of pasture utilisation (Baker and Leaver, 1986), leading to lower efficiencies of land use and therefore reduced production per unit area. Acceptability to customers Lower stocking density systems may be more preferable to customers but the need for additional housing may cause concerns over new farm building developments. The additional costs incurred on the farm may make the final product less affordable to some. 6.5. Use of existing and 'traditional' farm buildings for multiple uses The use of ‘traditional’ farm buildings is common in sheep and pig farming systems. Multiple use buildings can be used for storage of feed or equipment at certain times of the year, and for lambing or rearing pigs at other times. Some traditional buildings may also be used for seasonal poultry rearing, e.g. turkeys. Although using multi-purpose buildings as livestock housing can offer additional income and employment opportunities to mixed farms, making best use of farm resources and boosting rural income, consideration of issues including biosecurity and suitability of housing is required. Older ‘traditional’ buildings may offer shelter, but may not provide optimum biosecurity protection from wild birds and rodents. Labour requirements for bedding and cleaning out may be higher, although this


might be offset by premium payments (e.g. straw-reared pigs), and traditional barns may be more difficult to thoroughly clean and disinfect between batches/multiple uses.

Farm biodiversity Traditional farm buildings are often used for nesting and roosting of birds and bats – new buildings tend to provide fewer opportunities for wildlife. Older buildings made from natural materials provide the greatest wildlife value. Control of rodents in traditional buildings needs to be carried out carefully to avoid poisoning more welcome wildlife – access to bait by birds and other animals needs to be prevented, poisoned rodent bodies need to be found and removed, and all old bait and containers need to be cleared and disposed of carefully. Animal health status High animal health status is more difficult to maintain in traditional buildings because they may not be suitable for wet cleaning and thorough disinfection. Floor, wall and ceiling surfaces may not be smooth and impermeable. Integrated farming methods Using buildings for different enterprises and purposes, according to the time of year is consistent with an integrated farming approach. Keeping livestock in traditional buildings may allow the use of home-grown feedstuffs at the farm of origin and provide fertiliser through the utilisation of manure. 6.6. Environment controlled to optimise production This relates mainly to indoor pig and poultry operations; there is good industry awareness, but it is difficult to fully achieve in outdoor systems. Artificial lighting is essential to maintain the optimum photoperiod for egg production and optimum broiler development (Bessei, 2006). Temperature control is also important for efficient production and optimum feed intake.

Farm energy consumption Active forms of environmental control (lighting, heating/cooling, and ventilation) require energy and are therefore expensive compared to no or passive methods of control. There may be potential to reduce overall energy consumption and to increase the use of renewable energy sources, particularly on smaller-scale sites. High–specification insulation levels in walls and ceilings, for example in new buildings, offers scope for lower heat input in winter and reduced fan operation in hot weather.

Farm ammonia emissions Ammonia concentrations in indoor pig-finishing units are not necessarily related to environmental conditions (Beskow et al., 1998). In enriched cage egg production systems, technologies have been developed that dry the manure and thus reduce ammonia emissions. However, these systems can use significant amounts of energy.


Animal welfare standards Environmental control is crucial to the welfare of all poultry, particularly for young stock and for poultry kept in higher stocking density systems. For broiler chickens, temperature, humidity, air and litter quality are particularly important (Jones et al., 2005). Variation in health and welfare is related to how well the in-house environment can be controlled (Jones et al., 2005).

Effect on livestock output or performance The thermoneutral zone for pigs depends on age, physiological stage (e.g. 16-24 °C for sows, 29-35°C for piglets), health status, and factors such as floor and bedding type. At lower temperatures, animals use more energy to keep warm, and therefore less for production (e.g. Mount et al., 1973), and at higher temperatures intake can be reduced (e.g. Johnston et al., 1999). 6.7. Use of natural ventilation systems Good ventilation in livestock housing will supply draught-free fresh air to the animals, remove airborne micro-organisms, moisture, dust and gaseous pollutants (NH3, CO2 and other gases). At warmer times of the year, good ventilation will also help remove heat from the building. However, at hot times of the year if there is no natural wind it can be difficult to prevent heat stress in housed livestock.

Farm energy consumption Naturally ventilated housing reduces electricity consumption compared with powered ventilation.

Farm ammonia emissions A well designed ventilation system will interact with other design features of the livestock housing, for example slatted flooring, to reduce the airflow that carries ammonia-laden air out of the building (Misselbrook et al., 2008). It can also help to keep litter in good quality in poultry systems.

Farm greenhouse gas emissions Snell et al. (2003) reported that an increased ventilation rate in dairy cow housing increases methane emissions but in naturally ventilated housing this depends largely on the local climatic conditions (in particular wind velocity). On the other hand, Jungbloth et al. (2001) suggested that outside conditions had no effect on methane emissions from dairy cattle housing, and that the rate was dependent on the diets of the animals. Naturally ventilated buildings (e.g. straw barns/tents for pigs) can have poorer control over temperature, and therefore there is a tendency for poorer feed conversion, hence increased requirement for feed and thus an increased lifecycle carbon footprint per unit of output (IS0205, 2005).

Farm dust emissions As for NH3 and GHG, well ventilated livestock houses also tend to emit higher volumes of dust unless the exhaust air is filtered (Maghirang et al., 1995).


Animal health status Dairy calves are particularly susceptible to respiratory disease. Good natural ventilation reduces air bacterial concentrations and thus reduce the risk of respiratory disease in calves (Hillman et al., 1992; Lago et al., 2006). Natural ventilation in buildings can reduce the house temperature. Buildings that are too hot can lead to heat stress in cattle, which can affect fertility and embryonic survival (Collier et al., 1982).

Protection against animal disease impact Good ventilation systems can reduce the incidence of cattle disease, particularly of respiratory disease. Preventing disease in dairy cows (indeed in any animals) is a far better option than treatment (LeBlanc et al., 2006).

Effect on livestock output or performance Heat stress can lead to reduced feed intake, and therefore reduced productivity of cattle (Collier et al., 1982). Therefore, ventilation is an important aspect of cattle housing at hot times of the year. Natural ventilation can make it difficult to make poultry housing light-proof, which is important for egg production and controlled photo-period. 6.8. Use of powered ventilation systems The importance of good ventilation in livestock housing is discussed in Section 6.7. Powered ventilation systems can be used to augment ventilation when natural (unpowered) methods are inadequate on their own. For larger indoor pig and poultry units, the use of powered ventilation systems is standard practice.

Farm energy consumption Powered ventilation systems increase energy (electricity) consumption compared with natural ventilation. However, modern control systems, fans and well designed inlet/outlets offer scope for lower energy consumption.

Farm ammonia emissions The use of powered ventilation systems, with defined exhaust vents enables additional engineering solutions to reduce ammonia emissions from livestock housing, if necessary. Ammonia emissions from livestock housing can be reduced through the use of air scrubbers or biotrickling filters fitted to air exhausts (Moorby et al., 2009a). Without filtration, powered ventilation can increase ammonia emissions (Blanes-Vidal et al., 2008) from livestock housing.

Farm greenhouse gas emissions As with ammonia, increased ventilation of livestock housing can increase emissions of GHG if not filtered (Blanes-Vidal et al., 2008).


Farm dust emissions Dust emissions can be affected by the design of powered ventilation systems. Side extract systems tend to direct dust downwards where it may be collected, whilst roof extract systems may allow dilution and greater dispersal, particularly with open-topped fans. As above, the installation of air scrubbers or biofilters to building air exhausts can reduce dust emissions from livestock housing (Moorby et al., 2009a). Electrostatic precipitators are also a proven, if expensive, method of reducing dust from vented air.

Farm odour & nuisance emissions Many malodorous compounds are carried on dust particles, and therefore methods of reducing dust emissions from livestock housing can also reduce odour emissions.

Effect on livestock output or performance Adding fans to an existing cooling system (e.g. water misters/sprinklers), can improve the cooling affect and promote production by dairy cows (Urdaz et al., 2006). Indeed, in some circumstances the use of misting systems (Section 6.12) has little benefit without the addition of fans to achieve a cooling effect (Armstrong, 1994). 6.9. Ventilation requirements efficiently delivered - optimum fan performance Ventilation fan type, quality, control, placement, energy efficiency and maintenance are all factors that contribute to the optimum control of livestock housing ventilation (Arnold and Veenhuizen, 1994). Poor ventilation through the use of inefficient or poorly maintained fans can have a significant impact on livestock health and productivity as discussed in Sections 6.7 and 6.8. 6.10. Use of renewable energy sources The potential for use of renewable energy sources on livestock farms depends on the farm type (livestock type), location, natural resource availability, and the willingness of the producer to change from current energy sources. Most micro-generation power options (other than stand-alone devices) typically require substantial financial investment, although if available such investment can be worthwhile in the long term through energy cost savings.

Renewable energy Renewable energy sources fall into a number of categories, including electricity generation using wind, solar, water or biogas power, and heat generation using heat exchange pumps, burning biomass crops and biogas. Photovoltaic (PV) cells generate electricity directly from solar irradiance. On a small scale this can be used to run electric fencing units or water pumps, ventilation fans and other small motors, or can be used to charge batteries for running lights during the dark. PV is particularly useful for providing power in remote locations without access to mains electricity.


Solar power can also be used for space and water heating, for crop drying for livestock or domestic housing on the farm. Wind energy can be used mechanically, e.g. for running water pumps, or through conversion to electricity to power any electrical activity. On a large enough scale, when production exceeds local (on-farm) demand, wind-generated electricity can be sold to the national power grid. A more limited option is micro-hydroelectric generation. This depends on the availability of water (preferably in a stored form, as a pond or lake) to power turbines for electricity generation. Manures produced from housed livestock and locally grown biomass crops can be used to generate biogas (methane or hydrogen) that can be used to generate electricity via a generator, and/or heat by combustion. Biomass crops such as Miscanthus and short-rotation coppice willow and waste products such as poultry manure (Phillips et al., 1999) may be used to co-fire power stations. Ground source heat pumps make use of the stable temperature of the soil to increase the efficiency of electric heating and cooling solutions. Typically used in domestic or commercial situations, the ground area available on many farms could be used as a heat exchange field, without disrupting normal field activities once installed. Ground source heat pumps are most efficient at lower air temperatures due to the temperatures below ground remaining constant while atmospheric temperatures drop. Therefore they are most suited to heating creep mats or underfloor systems inside well insulated pig buildings. Biomass crops, including wood and timber produced from farm woodland, can be used for heat generation and locally sourced woodchip for bedding and farm tracks, and wood for domestic fuel use. Local sourcing of woodchips would reduce transport energy use as well as helping to promote carbon sequestration through managed woodland use.

Farm greenhouse gas emissions Locally produced energy reduces fossil fuel use, both locally and nationally (taking into account the inefficiencies of the national electricity grid). Anaerobic digestion of slurries and manures helps capture methane emitted from them during storage, and even if this methane is flared off, as opposed to being used for electricity or heat generation, this represents a reduction in CO2 equivalent emissions because methane has a 100 year global warming potential of 25 times that of CO2 (Forster et al., 2007).

Effect on livestock output or performance Use of renewable energies on livestock farms would have no detrimental effect on livestock productivity. Using livestock manures as part of an energy generation system increases the overall productivity of the livestock system.


6.11. Use of heat recovery systems Heat recovery systems are widely used in milking parlours to help cool milk before it enters the bulk tank. The heat extracted from milk is typically used to provide warm water for washing purposes. Pre-cooling of milk using a heat exchanger reduces the amount of refrigeration required, and therefore reduces electricity use. Other forms of heat recovery in livestock enterprises are developing, for example for indoor nursery pigs and in broiler housing where recovered heat can be used to reduce brooding costs and to improve litter quality. Air source (and water source) heat pumps work on the same principle as ground-source pumps but extract heat from the air using a fan that passes the air through an induction loop assembly compacted in an external wall unit. Warm exhaust air from building ventilation is a good source of heat. However, air from livestock buildings is very corrosive so the loops and foils within the pump must be made from noncorrosive materials. Air source heat pumps can also be used in reverse to aid summer cooling.

Farm energy consumption A plate heat exchanger reduces milk temperature from body temperature to approximately the temperature of the water used in the heat exchanger (e.g. 18°C). Further cooling by refrigeration equipment is required to the storage temperature of 4°C.

Renewable energy Energy in the form of heat from milk and excreta is a renewable resource and can be usefully used. Methane production from AD is optimised at around 35°C (Lin et al., 1987), which is self sustaining in hot climates, but can be helped by burning some of the biogas produced, through electrical heating or solar heating (e.g. Axaopoulos et al., 2001). Regular transfer of warm excreta from slurry stores into the AD plant minimises heat loss and therefore heating requirements of the process. 6.12. Use of sprinkling or misting systems In-house water sprinklers or misting systems can be used to help cool animals that are in danger of heat stress. Misting of oils can also help to reduce air pollutant emissions.

Farm ammonia emissions Misting or sprinkling systems in poultry housing that increase the moisture content of the litter tend to increase ammonia release (Carey et al., 2004), therefore equipment settings are important to achieve the correct balance between animal comfort and pollutant emissions.

Farm greenhouse gas emissions Misting essential oils with water in pig finishing sheds has been shown to reduce methane emissions (Ni et al., 2008).


Farm dust emissions Air concentrations of dust can be reduced by sprinkling oil/water mixtures in pig and poultry housing, thereby reducing dust emissions from force-ventilated buildings (Zhang, 1997; Carey et al., 2004; Nonnenmann et al., 2004).

Farm odour & nuisance emissions Many malodorous compounds are carried on dust particles, and therefore reducing dust emissions by in-house sprinkling or misting systems also tends to reduce farm odour emissions.

Animal welfare standards Pigs, which have no functional sweat glands, naturally use water and/or mud (wallows) to cool themselves in hot conditions. In hot weather, where temperatures rise above the pigs upper critical temperature, i.e. the thermoneutral zone, misting systems can be very effective at wetting the pigs’ skin and increasing evaporative heat loss, thereby lowering the upper critical temperature. For indoor pig units, where pigs do not have access to wallows, water misting systems allow evaporation to aid animal cooling. Powered ventilation systems in combination with misting systems enhance the cooling effect of evaporation. Water sprinkling and ventilation can also be used to cool cattle (Flamenbaum et al., 1986) and poultry (Tao and Xin, 2002).

Effect on livestock output or performance During hot conditions pigs help regulate body temperature by reducing feed intake, and therefore performance can be affected, particularly in heavier pigs (Quiniou et al., 2000). Cooling systems in pig finishing units are therefore important for optimum animal performance. The same is true for poultry. However, increased humidity can reduce rate of heat loss in the pig and depress appetite, thereby reducing performance (Smith, 1982). Similarly, heat stress in dairy cows can reduce productivity, and cooling through a combination of ventilation, with or without water misting, can help maintain feed intake and milk production (Igono et al., 1987; Frazzi et al., 2000; Frazzi et al., 2002). On the other hand, in outdoor hot conditions, provision of shade alone has been shown to reduce heat stress in beef cattle, with little additional effect of misting (Mitlöhner et al., 2001). 6.13. Use of energy-efficient or natural light sources This is most relevant to climate-controlled (indoor) environments in the pig and poultry industries, where there is growing interest and uptake in the use of energy-efficient lighting and natural light sources. In recent years, there has been increasing use of buildings for poultry which incorporate windows.

Farm energy efficiency Incandescent light bulbs are typically about 5% efficient in converting electricity to light. In Europe these are being phased out starting in 2009 and ending in 2012. More efficient lighting options include fluorescent tube lighting, compact fluorescent bulbs, high intensity discharge lighting, and light emitting diode systems. All of these systems produce similar levels of lighting using less electricity than a comparable


incandescent bulb, and may have a longer life and lower maintenance costs. Very little effect of changing lighting on poultry performance has been found (Lewis and Morris, 1998). 6.14. Use of light dimmers and timers to save power These are commonly used in the pig and poultry industry, particularly in farrowing houses/nurseries and in poultry systems.

Farm energy consumption Dimmer or automatically switching lighting typically save electricity consumption by not keeping lights on during the day, and maintaining dim conditions during periods of the night when full lighting is not required.

Animal welfare standards Use of intermittent (compared to continuous) lighting regimes has been shown to reduce the incidence of leg abnormalities in broilers (Buyse et al., 1996).

Effect on livestock output or performance Automatic lighting timers are also used to maintain the correct photoperiod required for laying birds to continue to produce eggs and for sows to enter the oestrous cycle earlier or later than normal in the breeding season. The growth rate of broilers may also be increased using intermittent lighting, compared with continuous lighting (Buyse et al., 1996). 6.15. Use of systems that allow animals free choice Allowing an animal free choice of certain behaviours is considered to be a fundamental concept for good animal welfare, which leads to good animal productivity.

Animal welfare standards The Farm Animal Welfare Council offers the concept of the ‘five freedoms’ for animal welfare: 1. Freedom from hunger and thirst 2. Freedom from discomfort 3. Freedom from pain, injury or disease 4. Freedom to express normal behaviour 5. Freedom from fear and distress None of these ‘freedoms’, which are the basis for good stockmanship, conflict with good animal productivity and animal product quality, with the possible exception of the freedom to express normal behaviour in some circumstances. A notable example of the above is the use of farrowing crates for sows, which is designed to reduce post-partum piglet mortality. The use of crates restricts sow movement, lack of bedding prevents nest building activity, and crated sows have


higher prepartum cortisol concentrations, indicating higher stress levels, than sows in straw-bedded pens (Jarvis et al., 1997). Nevertheless, indoor free-farrowing systems are still not universally proven to deliver sufficiently low piglet mortality to make them economically sustainable although research into free-farrowing alternative systems at a commercial scale continues. Livestock systems differ in the freedom of choice offered to animals – e.g. caged laying hens versus barn systems versus free range. The advantages of caged laying facilities include separation from droppings, low labour requirements, cleanliness of eggs, higher bird density, and lower feed requirements. Despite this, bird natural behaviour is restricted and therefore welfare is considered to be adversely affected. Barn and free range hens have more freedom to move and to exhibit natural behaviours such as dust bathing, roosting and perching. In the UK, conventional battery cages for laying hens will be banned from 1 January 2012, in line with EU Council Directive ‘Welfare of Laying Hens’ (1999/74/EC). After this date, caged hens will have to be kept in ‘enriched’ cages, which offer more space per bird and provide nesting, scratching and perching areas. Free-range livestock systems offer animals access to an outdoor environment. This may allow increased free-choice but does not necessarily mean higher animal welfare standards, if provision of shelter, protection from predation and suitability of land, among many other factors, are not adequately taken into account. Acceptability to customers The implementation of farming systems that allow greater free choice by animals is being driven by some assurance schemes and retailer production standards, largely as a means to improve customer product acceptance. 6.16. Use only of dry-clean methods for house cleaning Dry cleaning methods (e.g. scraping, brushing) are very seldom the only cleaning methods used for livestock housing. In some areas of the housing, e.g. cubicle passages in cattle sheds, automatic or manual (tractor) scraping is very common when occupied, but is likely to be augmented with a more thorough (wet) clean following unit vacation. Dry cleaning may also be employed in areas when fully drying an area is very difficult, e.g. in farrowing houses during the winter. In poultry systems, there is widespread use of wet-cleaning methods.

Efficiency of water use Dry cleaning at all times avoids the need for any water use. A combination approach, whereby thorough dry cleaning is followed by washing, reduces the overall use of water and targets it for maximum benefit. Areas that are resoiled almost immediately will not benefit from thorough cleaning, particularly by continuous occupation of a single group or batch of animals.

Protection against animal disease impact For optimum biosecurity, when animal housing is being vacated, either through depopulation or because of seasonal movement to outdoor areas, or between batches of animals, dry-cleaning only is likely to result in the potential for increased


disease transmission between animals. In addition, increased dust concentrations in animal housing air following dry-clean only methods is not good for human or animal lung health. Acceptability to customers Dry cleaning of housing for egg laying hens may increase the risk of zoonoses such as salmonella. Risk of water contamination incidents Wet cleaning of livestock housing can lead to potential pollution risks, unless dirty water is contained and handled effectively. 6.17. Use of recycled water for house cleaning The use of recycled water (e.g. from farm building roofs or a manure separator) for cleaning purpose is seldom used except for flushing manure from passageways and slurry channels.

Efficiency of water use Using lightly contaminated (non-potable) water for initial stages of cleaning or for use in flushing very dirty areas that are constantly resoiled, avoids the use of clean (mains or private supply) water. Recycled water can also be used for topping up wallows for outdoor sows, although care is required to prevent the spread of disease from one group to another if there is more than one group on the farm. Significant water storage facilities would be needed and water quality would have to be monitored. Animal health status The health status of animals could be affected by the use of recycled water, particularly if a final wash with potable water is not included. 6.18. Optimal use of chemicals during clean-out Chemicals (detergents, degreasers, disinfectants, bleaches etc) are typically used in cleaning operations, and the amount used is normally monitored for economic reasons. Although the use of too much cleaning chemical could be more expensive than necessary, the use of too little chemical could represent an even more severe economic penalty from poor cleaning and subsequent spread of disease.

Risk of water contamination incidents Lower chemical use could reduce the risk of contamination and pollution of local water-courses from run-off or washwater, particularly on sites that have no collection tanks. 6.19. Use of detergents/degreasers at clean-out Detergents may be used during clean-out in addition to or instead of disinfectants, bleaches and other cleaning agents. While cleaning agents can all help to reduce


water, labour and energy requirements, especially when used in combination with high pressure and/or hot water washing techniques, detergents are particularly useful for removing water insoluble residues. This is important in pig and poultry housing following depopulation in which oil misters or sprinklers (e.g. Nonnenmann et al., 2004) have been used to reduce dust concentrations. Efficiency of water use Use of degreasants and detergents have been shown to be very effective at loosening organic matter when used as part of a pre-soak routine, reducing power-washing time and therefore using less water.


7. Land and Soil Management

List of practices considered most important in the area of land and soil management and considered in this section. 7.1 Ensure suitability of land for outdoor livestock production 7.2 Use of paddock rotation 7.3 Use of field rotation - crops/animals 7.4 Outdoor area shared with other livestock 7.5 Maintain grass pastures at optimum heights, excess grass cut and utilised 7.6 Establish areas of vegetation on site, for conservation purposes 7.7 Construct wetlands, swales for water treatment 7.8 Use of multiple field entrances 7.9 Use of movable drinking water troughs 7.10 Use of cow tracks 7.11 Use of buffer strips/zones 7.1. Ensure suitability of land for outdoor livestock production Factors such as soil type, drainage, slope, altitude, precipitation, proximity to local water courses, and animal species all contribute to the suitability of land for livestock production. Suitability, in this context, is defined as the land supporting the grazing of animals on outdoor pastures. Problems mainly arise in wet conditions, and damage to soil following excessive trampling or poaching can lead to significant reductions in pasture growth (see Drewry et al., 2008, for a review) and hence land productivity. This is particularly so in areas used for outdoor pig rearing (Miao et al., 2004), although rooting in soil can have positive health benefits for pigs (Kleinbeck and McGlone, 1999). Compaction through excessive rooting or grazing at inappropriate times of the year can be alleviated through tillage operations, either as part of a crop rotation or reseeding for short term leys, or as land management practices such as subsoiling of permanent pastures.

On-farm flooding and / or erosion Risk of water contamination incidents Soil management and fertility Soil compaction following outdoor livestock production can reduce water infiltration rates (Daniel et al., 2002), which potentially leads to greater risks of flooding and contamination of local water courses with excreta-contaminated run-off during periods of heavy rainfall. These issues can be exacerbated with outdoor pigs where, unless the sows are fitted with nose rings, the paddocks will generally become areas of bare soil due to rooting activity. In this respect, outdoor pigs herds have considerable potential for harm to the environment through damage to soil structure, soil erosion, and direct and diffuse pollution of ground waters. Choice of sites for outdoor pigs that are suitable for soil type, topography and rainfall, are key aspects in mitigating many of these problems. On sloping sites for outdoor pig production, setting out paddocks so that service roadways run across the site rather than down the slope is an effective means of preventing a ‘water chute’ effect in periods of above-average rainfall. At these times


soil sediment and faecal contamination can be rapidly transported downhill to the nearest watercourse. Buffer strips of grass (also known as bunds) and/or areas of cover crops established across the bottom of an incline can intercept water flows to prevent soil erosion through run off. 7.2. Use of paddock rotation Summer grazing of pasture paddocks and housing during the winter is generally considered standard practice by dairy and beef farmers. Pasture swards may be defined as permanent pasture (i.e., land that has been under grass/grass mixtures for at least five years and is not ploughed for other crops) or short term leys (i.e., land that is resown with short-term crops, such as clover and Italian ryegrass). Paddocks may be grazed on a continuous basis or a rotation. Paddocks in the rotation may be of permanent pasture or short-term leys, and may include other livestock species in the rotation (e.g. cattle followed by sheep) to help increased pasture utilisation and reduce the infectivity of intestinal parasites. The amount of time animals reside in each paddock, and the amount of time between each residence period in each rotation can also vary, depending on sward growth rate and the use of paddocks for other purposes (e.g. silage or hay making). Outdoor pig units tend to rotate a set of paddocks on an 18-24 month cycle. Movement of arcs/finisher tents together with fencing, feed and water storage, and bedding storage requires more labour input than if animals alone are moved. For free range poultry, rotation is practiced either by moving the house itself to new land or (more frequently) by dividing the available land surrounding a static house into paddocks and controlling access.

Farm ammonia emissions Ammonia emissions from grazed livestock depends on the action of the hydrolysis of urea to ammonia. Rapid infiltration of urine into soil, where hydrolysis will occur, means lower rates of ammonia emission due to physical (the soil reducing air movements) and chemical (by adsorption of ammonium onto soil particles) means. However, rotational or set-stocking of grazing pastures is unlikely to influence these processes significantly. The use of a paddock rotation system for grazing livestock such as cattle provides more scope for applications of slurry throughout the grazing year than is possible on continuously grazed paddocks. Through the use of slurry injection or trailing shoe applications ammonia emissions can be significantly reduced (Smith et al., 2000; Misselbrook et al., 2002) at the same time as reducing sward contamination by slurry application.

Farm greenhouse gas emissions Use of paddock rotation for dairy and beef production also allows the use of crops such as red clover (Trfolium pratense), lotus (or birds-foot trefoil; Lotus corniculatus), and other forages that cannot tolerate prolonged heavy grazing.


Certain plant enzyme complexes (such as polyphenol oxidase – PPO – in red clover) and secondary compounds (such as condensed tannins in lotus) can influence the rumen microbial population, which can be beneficial in terms of improving the efficiency of food use and reducing pollutant outputs. Polyphenol oxidase in red clover has been shown to reduce proteolysis during the ensilage process (Jones et al., 1995), and more recently evidence for a similar effect at grazing of fresh red clover has been produced (Lee et al., 2009) leading to higher efficiencies of utilisation for milk production in dairy cows. Reducing proteolysis in the rumen should reduce the amounts of ammonia absorbed from the rumen and excreted in urine as urea, which contribute to ammonia and nitrous oxide emissions from grazed pastures. Condensed tannins in lotus can reduce the emissions of methane (Ramírez-Restrepo and Barry, 2005) and potentially ammonia (Misselbrook et al., 2005) in grazing dairy cows. Farmers using rotational grazing have the opportunity to record grass growth, and can make decisions about the need to fertilise a particular paddock based on grass requirements rather than blanket applications. In comparison, continuous grazing of a paddock make grass growth measurements more difficult. This should reduce direct emissions of N2O (Defra project ES0203), and indirect N2O emissions through reduced nitrate leaching.

Water quality Reduced use of fertiliser and fewer slurry applications to at-risk areas of land could reduce leaching of pollutants (N, P and faecal pathogens) to water courses.

On-farm flooding and / or erosion Soil structure is improved in ground with vegetation cover compared to bare soil, and water infiltration rate is related to grass cover. Therefore, grazing pastures reduce the risk of flooding as rates of run-off are reduced, assuming the soil is not saturated. However, there appears to be little difference between continuously and rotationally grazed pastures in terms of the amounts of water run-off and soil erosion (e.g. Gilley et al., 1996).

Protection against animal disease impact The health of several livestock species, including cattle, pigs and poultry, can be adversely affected by parasites found on range land. Paddock rotation can reduce the impact and therefore provide benefits to animal health. Intestinal parasites in ruminants are typically picked up through the consumption of infective larvae from pasture. The larvae mature in the gut of the host, shed eggs in faeces, which hatch into more infective larvae. Young and other uninfected cattle develop a parasite population when they are grazed on contaminated pastures. Rotational grazing does not reduce the risk of infection when the return to the same pasture is rapid (e.g. after several weeks regrowth) because nematode larvae can survive on the pasture for some time (e.g. Kristensen et al., 2006). However, longer rotations, or rotations including alternative grazing with other species, can reduce infection and provide ‘safe’ grazing for cattle (e.g. Fernandes et al., 2004; Larsson et al., 2007), thus requiring less use of anthelmintic drugs. Pastures are considered to be ‘clean’ (i.e. free of infection) following re-seeding, following silage or hay


production, or after having been grazed by a different species (i.e. sheep or horses, in the case of cattle).

Effect on livestock output or performance Rotational grazing tends to improve livestock output or performance, compared with continuous grazing. However, the optimum length of residence time in each paddock depends on pasture growth rates: longer residence during periods of fast pasture growth and shorter residence during slower pasture growth (Boyd et al., 2001). To maintain productive capacity, effective management of paddocks is required to ensure that optimum utilisation is achieved. For milk production a post-grazing sward height of 5 to 6 cm is considered optimum, and this can be achieved through a range of stocking rates and residence times (Delaby and Peyraud, 2003; Dale et al., 2008). Optimum post-grazing sward heights for sheep are generally considered to be 1-2 cm lower than those for cattle. Sequential grazing of sheep and cattle in a rotation system can lead to improvements in lamb live weight gain when following cattle (Wright et al., 2001) or goats (del Pozo et al., 1998) but not when following sheep (Wright et al., 2001). Provision of safe good quality food For laying hens, paddock rotation reduces the risk of intestinal worm infestations leading to internal contamination of eggs in the oviduct.

Integrated farming methods Rotational grazing fits well into integrated farming methods, encouraging the use of crops that can improve soil fertility (Watson et al., 2002), improve nutrient use efficiency (Watson et al., 2005), reduce pollutant emissions, and reduce parasite burden. Rotational grazing can also be used with permanent pastures, which have a different set of criteria – much of the carbon emissions from farming originate from soil cultivation.

On-farm use of chemicals There is potential to reduce the use of anthelmintic drenches (for all livestock species), to which resistance by nematodes in some areas is an increasing problem (Stafford and Coles, 1999; Lawrence et al., 2007).

Farm biodiversity Rotationally grazing pastures, compared with continuously grazed pastures, are likely to provide an increased range of habitats for invertebrates and other animal species that feed on them (Soderstrom et al., 2001). Guretzky et al. (2007) found floristic diversity to be significantly reduced on a small scale but not over large areas in paddocks rotationally grazed, compared to continuous grazing by cattle, which was also found by Hickman et al. (2004). A potential problem with rotational paddock grazing is the desire of farmers to have flexibility in paddock size, and therefore a possible desire to remove hedgerows around smaller fields and replace with moveable electric fencing. This would reduce the habitat value of the land and reduce biodiversity.


7.3. Use of field rotation - crops/animals Summer grazing of pasture paddocks and housing during the winter is generally considered standard practice by dairy and beef cattle farmers. Pasture swards may be defined as permanent pasture (i.e., land that has been under grass/grass mixtures for at least five years and is not ploughed for other crops) and short term leys (i.e., land that is resown with short-term crops, such as clover and Italian ryegrass). On mixed (or neighbouring) farms with livestock and arable crops, fields may be used in a rotated that incorporates forage for grazing and arable or horticultural crops for processing or human/animal consumption. Outdoor pig production is based on rotation principles, with pigs normally following undersown cereals and preceding (or sometimes following) potatoes, when they act as an alternative to chemical control of weed species and volunteer crops.

Farm energy consumption Rotational use of fields for forage and arable cropping requires greater energy use for cultivation purposes compared with permanent pasture used for grazing only.

Farm greenhouse gas emissions Use of field rotation for dairy and beef production allows the use of crops such as red clover (Trfolium pratense), lotus (or birds-foot trefoil; Lotus corniculatus), and other forages that cannot tolerate prolonged heavy grazing. Certain plant enzyme complexes (such as polyphenol oxidase – PPO – in red clover) and secondary compounds (such as condensed tannins in lotus) can influence the rumen microbial population, which can be beneficial in terms of improving the efficiency of food use and reducing pollutant outputs. Polyphenol oxidase in red clover has been shown to reduce proteolysis during the ensilage process (Jones et al., 1995), and more recently evidence for a similar effect at grazing of fresh red clover has been produced (Lee et al., 2009) leading to higher efficiencies of utilisation for milk production in dairy cows. Reducing proteolysis in the rumen should reduce the amounts of ammonia absorbed from the rumen and excreted in urine as urea, which contribute to ammonia and nitrous oxide emissions from grazed pastures. Condensed tannins in lotus can reduce the emissions of methane in grazing dairy cows (Ramírez-Restrepo and Barry, 2005).

On-farm flooding and / or erosion Soil structure is improved in ground with vegetation cover compared to bare soil, and water infiltration rate is related to grass cover. Therefore, grazing pastures reduce the risk of flooding as rates of run-off are reduced, assuming the soil is not saturated. However, there appears to be little difference between continuously and rotationally grazed pastures in terms of the amounts of water run-off and soil erosion (e.g. Gilley et al., 1996)

Protection against animal disease impact Intestinal parasites in ruminants are typically picked up through the consumption of infective larvae from pasture. The larvae mature in the gut of the host, shed eggs in faeces, which hatch into more infective larvae. Young and other uninfected cattle develop a parasite population when they are grazed on contaminated pastures.


Longer rotations including non-forage crops thus requiring less use of anthelmintic drugs. Pastures are considered to be ‘clean’ (i.e. free of infection) following re-seeding.

Effect on livestock output or performance Rotational use of fields with reseeded forage crops enables the most recent plant varieties to be selected for incorporation into the grazing sward. These could include grasses or legumes that improve animal performance through increased dry matter digestibility.

Integrated farming methods Rotational grazing fits well into integrated farming methods, encouraging the use of alternative crops that can improve soil fertility, improve nutrient use efficiency, reduce pollutant emissions, and reduce parasite burden. Rotational grazing can also be used with permanent pastures, which have a different set of criteria – much of the carbon emissions from farming originate from soil cultivation.

On-farm use of chemicals Potential to reduce the use of anthelmintic drenches, to which resistance by nematodes in some areas is an increasing problem (Stafford and Coles, 1999; Lawrence et al., 2007).

Sustainable management of land Crop rotation systems have been practiced in some parts of the world for hundreds or thousands of year. The Four-Field Crop Rotation system introduced by Charles Townshend in the 18th century helped start the British agricultural revolution, and many of the principles are as relevant today as they were three hundred years ago. 7.4. Outdoor areas shared with other livestock Cattle, particularly beef cattle, are often grazed on the same pastures with sheep. It is seldom done to any great extent with poultry or pigs on a commercial scale although small numbers of sheep can be used with poultry to maintain the grass at a manageable level in summer. Shared grazing can lead to increases in pasture utilisation as each species uses different parts of the sward – sheep are more selective grazers than cattle. In addition to leading to more efficient production (greater productive output per unit area of land), the ‘dilution’ of one species with another can improve certain aspects of animal health. Care must be taken to avoid overstocking, and cattle can cause more trampling than sheep, but this may have environmental benefits in terms of opening up a sward to increased floristic biodiversity. Farm energy consumption If sheep are not included, grass on free range poultry units needs to be cut mechanically in summer, a process that involves the use of energy.


Protection against animal disease impact Mixed grazing compared to single species grazing can reduce the intestinal parasite burden of at least one of the species (Brelin, 1979).

Environmental benefits Mixed grazing can produce a sward canopy that differs from that of pastures grazed by a single animal species only. This can alter the habitat value for invertebrate species (Dennis et al., 2001), which while not necessarily better, is different and therefore increases the biodiversity value together with swards grazed by single species. Increasing the invertebrate population of pastures can help to support bird populations, and the greater heterogeneity of sward structure generated by mixed grazing can help this, resulting in a greater abundance of birds (Evans et al., 2006b). Small mammal populations can also be affected: swards grazed by both cattle and sheep were found to support higher populations of voles than swards grazed by sheep only (Evans et al., 2006a)

Effect on livestock output or performance Mixed species grazing can improve livestock output by increasing live weight gain of at least one of the species. This tends to be through an increased efficiency of utilisation of available forage resources because the different species can utilise different sward components (Sehested et al., 2004), and also because of the willingness of animals to graze near the faeces of different species (Trotter et al., 2006). When cattle and sheep are grazed together, live weight gains of sheep (lambs) tend to be improved without an improvement of cattle (calf) gain (Brelin, 1979; Abaye et al., 1994; Cid and Brizuela, 1994; Marley et al., 2006a; Wright et al., 2006; Fraser et al., 2007a), but this is not always found (Critchley et al., 2008). Some authors have found that lambs grow best when mixed with growing cattle, but this can affect cattle performance (Olson et al., 1999; Kitessa and Nicol, 2001). Similarly, the ability of small ruminants (sheep and goats) to select more effectively than larger ruminants (cattle) means that sheep are may be able to consume an nutritional diet and keep growing, when cattle lose weight on the same vegetation (Celaya et al., 2007). Although mixed stocking can increase the daily live weight gains of individual animals, leading to more efficient forage utilisation, the output per unit area of land is frequently seen to be the same for single-species or mixed-species grazing.

Soil management and fertility Mixed grazing can improve soil fertility and sward structure as long as there is no overstocking. For example, differential selection of sward components by livestock species can change the sward botanical composition. Cattle can cause more trampling than sheep, which can open up the sward on, e.g. semi-natural rough grazing, to allow the ingress of other plans, but severe trampling can lead to poaching and damage of the soil structure.


7.5. Maintain grass pastures at optimum heights, excess grass cut and utilised

Different species of livestock perform optimally with grass at different sward surface heights, depending on their grazing habits and size (Illius and Gordon, 1987). In general, best productivity can be achieved with continuously grazed sward surface heights of about 7 cm for dairy cows (Gibb et al., 1997), 8-10 cm for beef cattle (depending on the season; Wright and Whyte, 1989) and 3-6 cm for sheep (Penning et al., 1991). Continuously grazed swards with surfaces heights of higher than these indicate higher stocking rates are possible, and are at risk of spoilage; surface heights lower than this indicate potentially limited food intake of the animals and therefore limited productivity. For outdoor pig enterprises, excess grass is usually only relevant at extremely low stocking densities or in buffer areas adjoining paddocks and may need to be managed by topping. Similar management may be used for outdoor poultry enterprises, or mixed grazing with other species may be used to manage sward height. For all livestock species, but particularly for ruminant species, pasture management may include closed periods for appropriate areas (whole fields/paddocks, or areas managed with moveable/electric fencing) used for conservation cuts used for making silage or hay. 7.6. Establish areas of vegetation on site, for conservation purposes This is not widely practiced at present, and although there is scope to implement this for some operations, others (e.g. intensive pig and poultry) may have little space to do this. Many farms that raise game birds for shooting plant areas of vegetation (e.g. stands of maize) as cover for the birds. Similarly, the planting of trees and hedges on land used by free range laying hens has become popular. Whilst it is done mainly to encourage ranging, it also makes a positive contribution to biodiversity although a potential drawback is the increased risk of rodents.

Farm biodiversity Much of the wildlife associated with farmland depends on habitats and food resources that can only be maintained through appropriate management activities. Diversity of habitat supplies resources for a diversity of wildlife, and therefore habitat heterogeneity, at a range of scales, is important for farmland wildlife (Benton et al., 2003). For example, farmland birds require three things to thrive: nesting sites, summer food and winter food. Individual species’ requirements differ, and therefore a variety of nesting sites and food sources are needed. Hedgerows are the main nesting habitat for a wide range of farmland birds (Hinsley and Bellamy, 2000), and many mammals (e.g. dormice and the greater horse-shoe bat) also make use of hedgerows and the associated grass margins at their base. A range of hedge types supports a wider range of hedgerow wildlife than a single type (Hinsley and Bellamy, 2000). Hedgerow plants also provide a range of food, from insects to berries, for a range of wildlife, and hedge trimming activities should be


carried out in such a way as to avoid disturbing nesting birds (March to August) or removing food sources (e.g. by trimming on rotation). Some existing areas of vegetation can be managed differently to increase the conservation value of land. For example, allowing areas of grass swards to flower and set seed (rather than being grazed or cut) can provide food resources for farmland birds over the winter (Defra project BD1455(322); Buckingham and Peach, 2006). 7.7. Construct wetlands, swales for water treatment Wetlands and other biological water treatment areas can be a useful addition to farmland (Cronk, 1996). In addition to providing an environment that encourages microbial activity to reduce the biological oxygen demand (BOD) of agricultural wastewater, they can act as habitat resources for farm wildlife. Not all farming operations would have sufficient space resources to construct wastewater treatment wetlands.

Water quality Constructed wetlands have been demonstrated to improve water quality by reducing concentrations of pollutants and excess nutrients through natural processes of soils, microbes and vegetation (Werker et al., 2002). Planted gravel-bed wetlands have been shown to be better at reducing pollutant outflow than unplanted gravel-beds (Tanner et al., 1995a; b). Rates of suspended solids removal and decrease in BOD depends on inlet concentrations and retention time, and therefore constructed wetland design must incorporate appropriate areas and pretreatments (such as solids separation) to maintain the wetland biota health (Knight et al., 2000). On pig and poultry farms, the use of constructed wetlands has been suggested as a suitable treatment method for lightly contaminated rainwater that falls onto roofs, concrete aprons etc. 7.8. Use of multiple field entrances Field entrances (i.e. gateways) along with food and drinking troughs (Section 7.9) tend to be the most heavily used part of the field and are therefore subject to soil compaction and poaching if wet. Use of multiple field entrances can reduce the traffic at a single point and therefore reduce the disturbance to the soil in the local area. This is particularly relevant to dairy systems in which cows are moved to and from the milking parlour at least once per day and therefore need to exit and enter grazing paddocks before and after milking. It is also relevant for outdoor pig production where daily transportation of feed and bedding can increase poaching of a limited number of field entrances. A related issue is the condition of land directly outside the popholes on free range poultry systems, since this can suffer similar problems of compaction and poaching. The use of slatted or gravel areas outside the popholes can help to maintain the ground condition.


Risk of water contamination incidents Poached and compacted soils are more prone to water run-off, which is likely to contain high concentrations of N, P and faecal organisms originating from animal excreta (Cuttle et al., 2007). Reducing traffic through one particular field entrance will reduce the potential for soil damage and thus the risk of contamination incidents.

Farm biodiversity Increasing the number of field entrances through a hedge is likely to have an adverse effect on the use of that hedge for wildlife (Hinsley and Bellamy, 2000; Benton et al., 2003). 7.9. Use of movable drinking water troughs Drinking troughs attract animals, which can lead to severe local soil damage (poaching and compaction) around the trough, particularly in wet conditions. This can lead to anaerobic conditions in the soil, coupled with high N and carbon contents due to grazing deposits. Such conditions are favourable for direct N2O and, to a lesser extent, CH4 emissions (Moorby et al., 2007). Movable drinking troughs allow management of the land to avoid soil poaching and compaction in one particular area. This is likely to be impractical for swards managed by strip-grazing using electric fencing. Fine-textured, less-permeable soils are most susceptible to poaching and the risk is increased in high-rainfall areas.

Risk of water contamination incidents Losses of N, P and faecal indicator organisms is likely to be reduced as a result of reduced poaching and water run-off (Cuttle et al., 2007).

Animal welfare standards In addition to potential reduction in GHG emissions, poached and muddy soil that animals must traverse to drink leads to dirty animals. This can be a particular problem for dairy cows with large udders, which require intensive cleaning before milking.

Animal health status For high levels of biosecurity, particularly in outdoor poultry farms, it is important that drinking systems are designed and positioned in a way that minimises contact with wild birds, to reduce the chances of disease spread. 7.10. Use of cow tracks Dairy cattle need to move between the milking parlour and grazing pastures at least once a day. Cow tracks minimise this movement time, maximise the access of grazing areas, reduce poaching in gateways (see Section 7.8), and can minimise damage to the animals’ hooves with improved walking surfaces. Bark or wood chippings, compacted stone and concrete are all possible materials for cow tracks, listed in increasing order of expense and durability.


Risk of water contamination incidents Less poaching in fields will reduce the risk of contaminated run-off (Sections 7.8 and 7.9).

Animal health status Cleaner cows resulting from them being less muddy walking to/from the parlour will improve in-parlour hygiene and may help reduce the incidence of mastitis. Properly maintained cow tracks (i.e. dry, firm, free of sharp stones) will also help to reduce the incidence of lameness (Blowey, 2005).

Effect on livestock output or performance Maintaining hoof health, minimising damage to sward surfaces and reducing the time cows spend walking to and from the parlour will all contribute to enabling cows to maximise energy expenditure on milk production and minimise it on other processes. 7.11. Use of buffer strips/zones Buffer zones or strips are areas of land used to separate two otherwise adjacent areas. They are frequently used to separate grazed or cultivated land and water (streams, rivers, ponds and lakes), and therefore may constitute the riparian zone. By not cultivating, fertilising, grazing or otherwise using these zones for agricultural purposes (although trees are sometimes planted), buffer strips can help reduce the effects of agriculture (e.g. nitrate leaching) on water quality (Correll, 2005), at the same time as providing wildlife corridors, and areas for small mammals and birds to feed and nest.

Farm ammonia emissions Ungrazed buffer zones are unlikely to affect ammonia emissions because the majority of ammonia is released from excreta deposited by grazing animals.

Farm greenhouse gas emissions Although buffer zones can effectively reduce the N content of run-off water, by acting as a kind of filter between actively managed soils and water courses, they can also be significant emitters of N2O as captured nitrate is denitrified (Hefting et al., 2003). This is likely to be due, in part, to the wetter soils near surface water courses leading to anaerobic conditions that promote denitrification processes. Nitrous oxide emitted from water courses capturing water from agricultural land is mainly that which is dissolved in drainage water, and only a small proportion is generated from dissolved nitrate (Reay et al., 2003; Weymann et al., 2008).

Water quality In addition to nutrients added to land by spreading manures, grazing ruminants can deposit large quantities of manure onto land. Practical management approaches to avoid the pollution of water courses include fencing and bridging to exclude animals, and the use of buffer strips to filter nutrients (Hay et al., 2006) and pathogens (Williams et al., 1999) deposited onto land close to the water. The effectiveness of buffer zones to reduce suspended solids and nutrients (total N, nitrate, total P and


soluble P) has been shown to be very variable, ranging from almost complete removal of pollutants to substantial increases (Cuttle et al., 2007; Kay et al., 2009).

Risk of water contamination incidents As above, use of riparian buffer strips has been shown to be variable in its effectiveness for reducing contamination of watercourses by nutrient pollutants (N and P) (Kay et al., 2009). Similarly, buffer zones can be effective (to a varying degree, from 30% to nearly 100% reduction) in reducing water contamination by herbicides and pesticides (Kay et al., 2009).

On-farm flooding and / or erosion Riparian buffer strips can reduce bank erosion and soil (sediment) contamination of the adjoining water courses (Lyons et al., 2000). The porosity of soils in ungrazed grass and agroforestry buffer zones is greater than that of grazed soils (Kumar et al., 2008), which may allow greater drainage through those soils. This, depending on the topography of the land, may help to reduce flooding incidents and erosion of topsoils by run-off.

Farm biodiversity Use of grassy margins/buffer strips can benefit invertebrate populations and thus bird populations, as a source of food and also for nesting areas (Bradbury and Kirby, 2006).


8. Enterprise Type

List of practices considered most important in the area of enterprise type and considered in this section. 8.1 Small unit size - below IPPC threshold 8.2 Large unit size - above IPPC threshold 8.3 Use of traditional breeds (less productive, slower growing etc.) 8.4 Use of carefully-bred, productive breeds 8.5 All stock home bred or home reared 8.6 Switch to all-in, all-out batch production 8.7 Reliance on artificial insemination 8.8 Extended cycle length, less frequent stock movement 8.9 End weight: High, Medium, or Low 8.10 Extended grazing of dairy cattle 8.11 Increased stocking density 8.12 Outdoor pig rearing 8.13 Upland beef and sheep finishing

8.1. Small unit size - below IPPC threshold The Pollution Prevention and Control Act 1999 was the UK implementation of the EU Integrated Pollution Prevention and Control (IPPC) Directive (Directive 96/61/EC), which regulates pollutant emissions to air, water and land from certain industrial activities. IPPC aims to prevent emissions and waste production, and where this is not practicable, reduce them to acceptable levels. This is achieved through permit conditions by the use of ‘best available techniques’ (BAT). The Pollution Prevention and Control Regulations were replaced on 6 April 2008 by Environmental Permitting Regulations (EPR), following the publication by the Commission on 21 December 2007 of a proposal for a Directive (COD/2007/0286) on industrial emissions [Industrial Emissions Integrated Pollution Prevention and Control (IE(IPPC)D)]. This proposal recasts seven existing Directives related to industrial emissions into a single legislative instrument, including the IPPC Directive. Under EPR, ‘industrial sources’ of emissions include intensive indoor rearing of pigs and poultry, defined as 40,000 places for poultry, 750 places for sows, or 2,000 places for production pigs over 30 kg (Directive 96/61/EC). Outdoor pig sites do not fall within IPPC. The new IE(IPPC)D proposal separates poultry into different sized birds, with thresholds of 40,000 broilers, 30,000 layers, 24,000 ducks and 11,500 turkeys; for other species numbers will be calculated according to equivalent nitrogen excretion factors. The proposal also now includes the spreading of livestock manure on land outside of the pig and poultry units, which is currently not covered by BAT regulations. In the proposal, operators will be required to used BAT for manure and slurry spreading activities. Economies of scale for pig and poultry enterprises mean that unit and house sizes have tended to increase. This is not only the case for intensive systems but also for many free range systems. Some specialist free range and organic producers have remained small, since this is considered to be consistent with consumer requirements. In addition, some who are close to the IPPC thresholds have chosen


not to stock at higher levels (i.e. above the threshold) for ease of operation and to avoid regulatory costs.

On-farm flooding and / or erosion With potentially fewer buildings per area, there is reduced risk of flooding and erosion from water run-off.

Rural employment Smaller unit size means a higher labour input per unit output, leading to more rural employment for more, smaller farms compared with larger unit sizes. 8.2. Large unit size - above IPPC threshold For the intensive poultry and pig sectors, large unit size is considered essential for profitable operations. Larger units typically have lower feed costs, lower energy inputs, lower labour inputs, and therefore lower production costs, per unit output than smaller units. Transport efficiency of inputs (feeds, replacement animals) and outputs (eggs, finished animals) is also increased with scale, leading to lower running costs and lower pollutant output per unit of finished product. Emissions of pollutants (ammonia, GHG, dust and odours) from large production units should be reduced through the use of BAT as part of the IPPC regulations. Management plans are required for the EPR permit. If proposals for BAT regulations to cover the spreading of manure and slurry on land surrounding pig and poultry operations are introduced, further reductions in gaseous emissions may also be achieved.

Animal health status Very high standards of biosecurity and disease prevention are required for large pig and poultry units. The outbreaks of influenza A virus subtype H5N1 (‘bird flu’) in East Anglia in 2007 highlight the risks of large poultry production operations, using both indoor and outdoor (free-range) methods. Clearly, good health plans are required for all operations, but the larger the operation the higher the potential economic impact of losing the stock. 8.3. Use of traditional breeds (less productive, slower growing etc.) Within each livestock species (e.g. cattle, sheep etc.) a small number of breeds predominate. For example, the most important dairy breeds (by population size) are the black and white breeds (including Holstein-Friesian, Friesian, Holstein, British Friesian) of which there are approximately 2.9 million in the UK, while the most important beef breed is the Limousin, of which there are approximately 1.9 million in the UK (Defra, 2008). The stratification of the sheep industry means that a number of breeds predominate depending on farm location, ranging from Scottish Black Face and Welsh Mountain sheep in the hills and uplands to Suffolk and Texel breeds predominating as the terminal sires for meat production. For poultry, brown hybrid


strains dominate the egg laying sector whilst white-feathered hybrids are mainly used for table chicken and turkey production. Similarly in the pig industry, hybrid strains based on selected lines of major breeds, such as Large White, Landrace and Duroc predominate in female breeding stock with increasing use made of breeds such as Hampshire and Pietrain in the sire line to enhance carcase quality and finishing performance. There is considerable variation among livestock breeds (and even within breed) on the productivity and other characteristics of the animals. There are also many traditional breeds, defined as those that were bred for a specific locality and climate, and typically these have a lower productive capacity than the more popular breeds, mainly as a result of less intensive breeding programmes. Some traditional breeds such as the Aberdeen Angus and the bronze turkey may be considered to be superior in terms of eating quality. There is much speculation and opinion on the utility of the use of traditional breeds in terms of their environmental sensitivity. Slower growing animals tend to be less efficient than faster growing animals because the same amount of product is produced over a longer period, during which the maintenance energy and protein requirements of the animals must be met in addition to growth requirements, and the animals continue to excrete waste products for longer than faster growing animals that are slaughtered at an earlier age. Similarly, lower yielding dairy cows use a higher proportion of their energy and protein consumption to meet maintenance requirements compared with higher yielding cows.

Farm ammonia emissions Traditional livestock breeds tend to be less efficient (lower yielding/slower growing) than modern breeds and therefore consume more feed and excrete more nitrogen per unit output.

Farm greenhouse gas emissions Similarly, traditional breeds tend to produce more GHG per unit output. However, for dairy cows there is considerable interest in using traditional or alternative breeds (e.g. Channel Island, Montbeliarde) in crossbreeding programmes to gain the benefits of heterosis (hybrid vigour), particularly with the aim of increasing the longevity of the animals. Increasing the longevity of cows is expected to decrease CH4 emissions and increase lifetime N use efficiency, although the inefficiencies of N use introduced by replacement cows is very small compared to those of milk production by mature animals (Defra project IS0213). However, it should be noted that dairy cows must breed to lactate and a reduction in livestock numbers can only be achieved with improved fertility in dairy cows if the dairy-bred calves can replace beef-cow calves, i.e. a beef bull is used to produce an animal destined for meat in place of a replacement dairy heifer. Garnsworthy (2004) estimated that restoring fertility levels to 1995 levels (averages of 72 days to first insemination, 55% oestrous detection rate, 47% conception rate at first service, and 46% conception rate at subsequent services) would reduce CH4 emissions by 10-11%. Further improvements in these values (reduced time to first service, improved oestrous detection and conception rates; see Garnsworthy, 2004) could reduce CH4 emissions by up to 24%.


Effect on livestock output or performance In farming systems that rely on high yields or fast growth rates for economic sustainability, the use of less productive breeds is a disadvantage. In sheep, traditional breeds may kill out at a lower weight with the resultant carcasses having poorer conformation than more modern breeds (Hall and Henderson, 2000), albeit perhaps without economic penalties. Among dairy cows, modern black and white cows with high yields need high feed inputs to maximise efficiency. Traditional livestock breeds may be more suited to lower-input systems (Edwards, 2005), perhaps with lower grow rate or milk yields, but for the latter with less reliance on body reserves than higher-yielding breeds (Dillon et al., 2003). Commercial lines of laying hens have displayed earlier sexual maturity, greater rate and persistency of lay and higher egg weights than traditional breeds at certain times of their productive life, although this was at the expense of some physical traits like bone strength (Hocking et al., 2003). Modern breeds of pigs can be faster growing than traditional breeds (Wood et al., 2004), but even when there is little difference in growth rates between pig breeds, carcass fatness can be greater for traditional breeds (Wood et al., 2004; Kelly et al., 2007). This can result in a twin disadvantage of lower payments to producers and less desirability of meat cuts with high levels of visible fat to consumers. However, more intramuscular fat in meat of all species can improve the eating quality of meat (tenderness, flavour, juiciness), and therefore command higher prices in specialist markets.

Animal welfare standards Although commercially successful livestock breeds may be more efficient and fast growing/higher yielding than traditional breeds, these benefits are correlated to a number of undesirable effects on reproductive, behavioural, and health characteristics (Rauw et al., 1998).

Farm biodiversity In a review of the effect of grazing and livestock breed on biodiversity indicators, Rook et al. (2004) found the effect of breed to be negligible, and largely related to breed size. 8.4. Use of carefully-bred, productive breeds Livestock farmers breeding their own replacement stock generally aim to improve their stock as a matter of course, although there is still considerable scope for improvement, particularly in the beef cattle sector. In the pig and poultry sector, breed improvements are mainly the result of the activities of breeding companies rather than farmers or production companies. Uptake of the best genetics is good in the dairy industry, largely through the use of artificial insemination (AI) in dairy herds. However, historical selection goals have focussed on production and did not include lower heritability traits such as health and fertility traits (leading to less ‘robust’ animals). Today, breeding goals in most species are more balanced to include these latter factors, but there is still much scope for health and fertility traits to catch up with growth- or yield-related traits. Recent Defra funded work (Defra LINK projects LK0657 and LK0645) has aimed to


increase dairy cow longevity through improved fertility and breeding more robust animals.

Farm ammonia emissions Garnsworthy (2004) estimated that restoring fertility levels of dairy cows to 1995 levels would reduce NH3 emissions by 9%, and further improvements could reduce NH3 emissions by 17%. Based on the figures from Defra project IS0214 (Del Prado and Scholefield, 2008) NH3 emissions from livestock are estimated to be reduced in the range 2-5% and subsequent NO3 leaching losses 1-3%.

Farm greenhouse gas emissions Increased efficiency of ruminant production through improvements in the supply and utilisation of end product beyond the farm gate would reduce production requirements and therefore GHG emissions commensurate with reduced livestock numbers. Reduced residual feed intake (consumption of feed above that required for production) is heritable and breeding programmes that incorporate this trait could result in a permanent reduction in CH4 output (Alford et al., 2006). Alford et al. (2006) estimated breeding for lower residual feed intake in beef cattle could reduce annual CH4 outputs by 3.1% on a national (Australia) basis, or to much greater reductions (up to nearly 16%) on an individual farm basis over a 25 year period. Individual ruminant animals can have innately reduced CH4 outputs, possibly associated with rumen protozoal populations, and may be of use in breeding programmes (Goopy et al., 2006). Increasing the longevity of cows is expected to decrease CH4 emissions and increase lifetime N use efficiency, although the inefficiencies of N use introduced by replacement cows is very small compared to those of milk production by mature animals (Defra project IS0213). However, it should be noted that dairy cows must breed to lactate and a reduction in livestock numbers can only be achieved with improved fertility in dairy cows if the dairy-bred calves can replace beef-cow calves, i.e. a beef bull is used to produce an animal destined for meat in place of a replacement dairy heifer. Garnsworthy (2004) estimated that restoring fertility levels to 1995 levels (averages of 72 days to first insemination, 55% oestrous detection rate, 47% conception rate at first service, and 46% conception rate at subsequent services) would reduce CH4 emissions by 10-11%. Further improvements in these values (reduced time to first service, improved oestrous detection and conception rates; see Garnsworthy, 2004) could reduce CH4 emissions by up to 24%. The estimates of project IS0214 (Del Prado and Scholefield, 2008) were more conservative (3% reductions for both N2O and CH4), but concurred that improvements in fertility would reduce direct GHG emissions.

Farm biodiversity In a review of the effect of breed on biodiversity indicators, Rook et al. (2004) found the effect of breed to be negligible, and largely related to breed size.


8.5. All stock home bred or home reared Home breeding and rearing of stock allows full control over a number of factors including livestock genetic improvement and biosecurity. For beef and dairy operations, one end of the spectrum is the closed herd system, while purchasing all replacement or finishing cattle is at the other end. Many larger pig operations have nucleus farms producing breeding stock for use within the company production pyramid, where health is regarded as equal between farms. Some smaller pig units also home-breed replacements using AI. Some integrated poultry companies (particularly in the poultry meat sector) have their own breeding and hatching facilities, but for egg producers the main issues are whether to home-rear replacement pullets from day-old chicks on the same site or elsewhere, or whether to buy in replacement pullets at point-of-lay.

Farm energy consumption Breeding and/or rearing all stock on site reduces transport costs associated with movement between sites. On the other hand, increased housing requirements are required for a range of livestock age-groups: breeding stock, young stock, and growing, finishing, lactating or laying stock. This can increase energy costs for climate and photoperiod control, if used, on a single farm, although across the industry the energy costs would be the same but in different locations.

Protection against animal disease impact Closed flock or herd strategies eliminate the importation of animals or older birds onto a farm. The purchasing of replacement or finishing stock carries the risk that those animals may be carrying a transmissible disease that could then infect the other animals on the establishment. Breeding and rearing replacement animals is, however, only one part of good biosecurity practice. A closed flock or herd strategy is likely to increase the overall size of the unit and therefore the impact of animal disease would be greater. See also Section 8.2 for other issues associated with increased unit size. 8.6. Switch to all-in, all-out batch production This is common practice in the poultry meat sector, and in excess of 55% of pig production is organised in this way.

Farm ammonia emissions Single age groups allow simple phase feeding, thereby allowing more accurate matching of diets to nutrient requirements for a given growth or physiological stage of pigs and poultry. Matching protein requirements in this way will reduce ammonia emissions (Misselbrook et al., 2008).

Efficient use of resources Specific activities each week allow an efficient use of labour, concentrating on a particular task in large operations.


Animal health status There are potential health benefits of having same-age groups of animals, with both behavioural (e.g. less bullying by larger animals) and lower infectious disease risks (i.e. allowing blanket coverage prophylactic treatments). Complete building depopulation also allows for buildings to be emptied, and thoroughly cleaned and disinfected between batches, which is not possible with continuous production systems. 8.7. Reliance on artificial insemination Artificial insemination (AI) is very common in the dairy (Vishwanath, 2003) and pig industries (Singleton, 2001; Gerrits et al., 2005; Brassley, 2007), with increasing use in the beef industry. Artificial insemination in sheep is limited by the anatomy of the ovine cervix (Wulster-Radcliffe et al., 2004). The rapid increase in genetic merit for milk production in dairy cattle over the last 20 to 30 years has relied heavily on AI (Vishwanath, 2003), allowing easy dissemination of genes from individual bulls into the global dairy herd. Reliance on AI reduces the need to keep bulls and boars, which is particularly relevant for smaller producers, thereby reducing housing and feeding requirements together with the associated dangers to farm labour. Careful breeding programmes are required to maintain genetic diversity in AI bred livestock and prevent inbreeding (e.g. not using a particular sire on one of his daughters), although AI can potentially also help maintain rare breeds of all species of livestock by enabling breeding of a female with a distant male. High levels of biosecurity at semen collection studs helps to minimise the risk of infection of valuable sires, and good lab techniques reduce the risk of bacterial contamination (Maes et al., 2008). These measures reduce the risk of sexually transmitted diseases to inseminated females. Farm staff need specialist training on oestrus detection to ensure optimum insemination timing, and also in semen collection and preparation (boars), and in insemination techniques. Many dairy farms that rely on AI also keep a bull, frequently of a beef breed, to inseminate any cows that are difficult to breed by AI. 8.8. Extended cycle length, less frequent stock movement A conventional dairy production cycle consists of annual calving, with a 305 day lactation period and a 60 day dry period. However, with increasing problems with fertility in dairy cows there is interest in increasing the lactation period in the cycle to reduce the need for getting the cow back into calf at a time of high milk yield. In egg production, laying hens are typically kept for around 56 weeks before replacement while in the poultry meat sector, the growing time is determined by market requirements for finishing weight (see Section 8.9). Potential benefits of extending the cycle length include a reduction in stock movements and fewer replacements being needed.


Animal health status A large proportion of dairy cow diseases and disorder occur during the transition period (the few weeks surrounding calving) (LeBlanc et al., 2006). Reducing the number of calvings, and therefore the number of relatively risky transition periods that a dairy cow must go through is likely to reduce the incidence of disease in a dairy herd. For laying hens, mortality rates typically increase with flock age and so extending the cycle length is likely to result in more fallen stock to be disposed of.

Acceptability to customers Dairy cows need to produce calves to lactate. Unless sexed semen is used, the chance of a cow producing a bull calf when she is served with a dairy bull for producing replacement animals is approximately 50%. The relatively low economic value of such dairy bull calves means that many are slaughtered at birth, a practice which many dairy producers and the general public are not comfortable with. Therefore, reducing the number of calves that dairy cows produce through extended lactation is likely to reduce the numbers of dairy bull calves produced and slaughtered at birth. However, the use of dairy bull calves in initiatives such as ASDA’s ‘Low Carbon Beef’ (ASDA, 2009) can also help alleviate this problem. In egg production, aspects of egg quality (e.g. shell colour, internal quality) tend to decline with flock age, so extended cycle length may not be acceptable to customers.

Effect on livestock output or performance Many dairy farmers operate a calving pattern that fits with their preferred choice of feed utilisation, either relying on fast grass growth to supply major feed resources for spring- and summer-calving cows, or conserved feeds for autumn-calving cows. Extending a cow’s lactation cycle beyond 365 days means that calving patterns become unsynchronised with feed resource patterns. A typical lactation curve for a dairy cow exhibits peak milk yields at approximately 6 weeks of lactation, following which milk yield declines to low yields at the end of lactation when the cow is dried off. The persistency of milk yield during the declining phase of the lactation curve is a major determinant of the economic returns from extended lactation (Esslemont and Kossaibati, 2002). On the other hand, high yielding cows with extended persistent lactations can be more profitable than cows with standard length lactations (e.g. Arbel et al., 2001). This is particularly so in the US, where recombinant bovine somatotrophin (rBST, growth hormone) can be used to boost milk yields in late lactation (van Amburgh et al., 1997). Similarly, in laying hens output declines with age and persistency is a major determinant of economic returns. 8.9. End weight: High, Medium, or Low The rate of live weight gain of standard exponential growth curve for growing animals declines as the animal gets older. Thus, feed conversion efficiency declines as the animal nears maturity. This is particularly so in animals reared for beef meat. For poultry and pig meat, broilers, and pigs reared for cutting or processing (ham, bacon etc), are produced according to customer contract requirements, which typically means a range of end weights. However, commercial pressures and advances in


carcass engineering at specialist pig processing plants have influenced an increase in carcass weight. For many animals, older animals have a higher proportion of carcass fat (e.g. Perreault and Leeson, 1992; Jurie et al., 2005), which is typically rejected by modern consumers. Therefore, younger, smaller animals may produce more desirable carcass characteristics, although this has to be offset against the economics of production, including transport and slaughter costs.

Farm greenhouse gas emissions By slaughtering animals at a younger age higher rates of feed use efficiency are exploited (Jurie et al., 2005). Feed intake is highly correlated to methane emissions (Ellis et al., 2007), so by slaughtering beef animals at a younger age, not only are methane emissions per animal reduced – because younger/smaller animals consume less food – but lifetime methane emissions are also reduced. The UK supermarket ASDA recently announced a new range of ‘low carbon beef’ based on the principle of producing beef from animals slaughtered at an age of 9 to 11 months old, compared to the more usual age of 24 months (ASDA, 2009).

Provision of safe, good quality food Beef tenderness reduces with age of the animal (Shorthose and Harris, 1990), so younger animals tend to provide better eating quality (hence veal and suckling pig), although in poultry meat flavour is generally considered superior from older birds. On the other hand, smaller/younger animals provide less meat per carcass, although the proportion of carcass that is muscle can be higher (Jurie et al., 2005) or similar (Sañudo et al., 2004). In addition, the use of dairy breed bull calves in initiatives such as ASDA’s ‘Low Carbon Beef’ (ASDA, 2009), which are otherwise frequently slaughtered at birth, provide a market for what may be viewed as an apparent waste. 8.10. Extended grazing of dairy cattle Extended grazing aims to reduce the amount of time that dairy cattle are housed over the winter period, with cows being grazed earlier in the spring and later in the autumn. This reduces the dependence on conserved forages, and maximises the utilisation of fresh forage. The ability of individual farmers to carry out extended grazing depends on cow genetics, local climate (particularly rainfall), soil type, and farm layout.

Farm ammonia emissions Ammonia emissions from grazing cattle are much lower than from housed cattle. This is mainly because urine, in which most of the ammonia-forming urea is deposited, rapidly infiltrates soil and any ammonia formed tends to stay there rather than being volatilised. In contrast, excreta deposited onto impermeable surfaces such as the floors of cattle housing provide a source of ammonia until it is removed. Webb et al (2005) estimated that extending the grazing period of dairy cattle by 2 month per year could reduce ammonia emissions by up to 10%. On the other hand, nitrate leaching would likely increase, both as a result of increased excreta deposition onto land, and also as a result of increased fertiliser N use. This would also likely lead to increased in direct and indirect N2O emissions. Increased nitrate leaching through extended grazing may contravene Nitrogen Vulnerable Zone regulations.


Farm greenhouse gas emissions Extended grazing may increase GHG emissions, particularly N2O emissions, as a greater proportion of excreted N is denitrified in the soil or following leaching of nitrates with drainage water. Emissions of N2O are highest when grazed pastures are wet, providing an anaerobic environment that encourages denitrification. Restricting autumn grazing in South Island, New Zealand, was found to reduce both N2O emission and nitrate concentrations in drainage water by about 40% (de Klein et al., 2006).

Efficiency of water use Depending on the system of cleanout, there is potential for less water to be used for the cleaning of housing, although the amount of water used during milking of dairy cows will be unchanged.

Risk of water contamination incidents There is greater potential for contamination of water courses if cows graze outdoors for longer during the year, particularly in wet months when increased rainfall may lead to run-off containing higher concentrations of faecal pathogens, N and P (Cuttle et al., 2007).

On-farm flooding and / or erosion If inappropriate grazing management is used during the wetter months of the year there is increased risk of poaching and soil compaction, and hence more surface run-off (Owens and Shipitalo, 2009). Bare patches of soil caused by poaching are also more prone to erosion on sloping ground.

Animal welfare standards The effects of extended grazing of dairy cattle on welfare depend on soil type and drainage, farm infrastructure including cattle tracks, and average temperature and rainfall in a given location. The Oklahoma Mesonet Cattle Cold Stress Index (University of Oklahoma, 2009) estimates increased energy requirements for beef cattle with wet coats from effective (i.e. including wind chill) temperatures of 15°C and lower, or 0°C and lower for animals with dry winter coats. Therefore, extended grazing associated with reduced use of housing (i.e. shelter) is likely to decrease the welfare of dairy cattle in poor weather conditions (Laven and Holmes, 2008). On the other hand, housed cows are more prone to lameness and mastitis problems than those living outdoors.

Effect on livestock output or performance Offering grazed grass to early lactation dairy cows for just 2 hours per day in spring, before normal turnout, increased milk yield and reduced silage intake compared to fully grazed cows (Sayers and Mayne, 2001). On the other hand, by turning out cows a week earlier than normal, Virkajarvi et al. (2003) found easier pasture management without affecting milk yields. Recently, Kennedy and O’Donovan (2008) reported that there was no effect on milk yields among extended grazing treatments ranging from full time access to grazing pastures to two 2-hour grazing periods following milking. They also investigated the use silage supplementation when the cows were indoors and although there was no effect on milk yields,


supplementing cows with silage (compared to no supplementation) reduced milk protein concentrations. There is potential to reduce output with extended grazing in adverse climatic conditions (i.e. cold and wet). Increased maintenance energy requirements of cold-stressed cattle would mean that there would be less energy for productive purposes.

Farm biodiversity Extending the grazing season to that pastures are grazed earlier in the year, and/or for longer during the year, means that use of those pastures by other species may be compromised. For example, Tichit et al. (2005) most bird species surveyed in grazed fields tended to prefer those with lower grazing intensities, although some species preferred more intensively grazed fields. 8.11. Increased stocking density Stocking density (or rate) is the number of animals allocated to an area of land or a building (e.g. cows/ha, birds/m2), and for grazing animal production the optimum stocking density for a pasture is a balance of the productive capacity of the sward and the number of animals grazing it. It is one of the most basic management tools that can be utilised with grazing livestock, and is dependent on the carrying capacity of the land area.

Farm energy consumption High stocking densities in pig and poultry units, particularly of young stock, result in more efficient use of space and lower heating energy requirements. Growing pigs in particular radiate a lot of heat (approximately 8-10 MJ/d).

Farm greenhouse gas emissions Methane emissions from the rumen are influenced by dietary factors and are correlated with feed dry matter intake (Johnson and Johnson, 1995). Therefore, stocking rate is frequently seen to have little effect on methane output when feed intake is unaffected, either expressed on the basis of animal live weight or as a proportion of gross energy intake (McCaughey et al., 1997; Pinares-Patiño et al., 2007).

Risk of water contamination incidents There is greater potential for water contamination with greater livestock stocking densities.

On-farm flooding and / or erosion Grazing can increase soil compaction and reduce water infiltration of the soil surface, which can be reduced with increased stocking density (Daniel et al., 2002). Therefore, high stocking densities of cows on grazed pastures or outdoor pigs and poultry may increase the risk of flooding during heavy rainfall as rates of water run-off could be increased.


Animal welfare standards Indoor broiler production tends to be particularly intensive, and while legislation is generally leading to lower stocking densities, this may not improve animal welfare as much as other factors such as the environmental conditions in which chickens are kept (Dawkins et al., 2004; Jones et al., 2005). Knowles et al. (2008) identified increasing stocking density to reduce flock gait score (i.e. the ease and ability with which the birds’ could walk), but also found gait score to be influenced by photoperiod, food pelleting, use of antibiotics in feed, and genotype. Health and welfare of broilers is compromised if space allowances rise above between 34 to 38 kg final body weight/m2 (Estevez, 2007). During periods of hot weather, the welfare of poultry kept at high stocking rates may suffer as a result of heat stress.

Environmental benefits Increased stocking densities (e.g. by the use of multi-tier principles for poultry) within a house reduce the size and total amount of houses needed for a given number of birds. The environmental impact of new buildings is therefore reduced.

Effect on livestock output or performance At stocking rates that limit herbage availability grazing animals are forced to graze deeper into the sward horizon, which can lead to the consumption of lower quality material (more stem and less leafy herbage). Limiting herbage availability beyond the carrying capacity of the pasture will reduce productivity, although making use of early spring grass growth by increasing stocking rate can improve sward utilisation (Baker and Leaver, 1986). On the other hand, undergrazing a pasture can lead to rank swards of relatively poor quality herbage, which will limit productivity on subsequent use. Even relatively small differences in stocking rate can lead to differences in sward quality (Kennedy et al., 2007; Pinares-Patiño et al., 2007). High stocking densities can reduce growth performance in pigs (Leek et al., 2004; Kerr et al., 2005), primarily as a result of physiological stress, although there appears to be interaction with housing type so that space allocation does not always influence growth or finishing characteristics (Patton et al., 2008). High stocking densities in pigs are also known to impact adversely on health.

Farm biodiversity Certain measures of biodiversity can decrease with stocking density, e.g. butterfly and grasshopper numbers, as the plants that support them are grazed out (Dumont et al., 2009). On the other hand, lightly and ungrazed pastures are less preferred by some wildlife to pastures with shorter sward heights (e.g. hares; Karmiris and Nastis, 2007), and bare pastures, produced by high stocking rates, are required by some farmland birds (Bradbury and Kirby, 2006). Similarly, higher inputs of organic matter from grazing animals (i.e. faeces deposition) can increase invertebrate numbers (Bates et al., 2007). There is clearly no single ideal system, and a biodiverse environment is achieved through heterogeneity of habitats.


8.12. Outdoor pig rearing Approximately 41% of the UK pig breeding herd is kept outdoors, the progeny being either moved indoors for rearing or remaining on the field site until about 40 kg liveweight before being transferred indoors for finishing. A very small (2-4%) but steadily growing number of pigs are born, reared and finished outdoors. Outdoor pig finishing systems may use conventional production methods and feeds or may be operated to specific organic standards. Outdoor pig production provides a valuable contribution to land rotation through enhanced soil fertility (manure deposition) and weed control although at the expense of increased potential for soil compaction, soil erosion, as well as direct and diffuse pollution risks.

Risk of water contamination incidents Rooting behaviour can cause substantial pasture damage, and although this can be mitigated to some extent, but not completely, by dietary manipulation (Braund et al., 1998). Loss of green cover can result in risk of excess nutrient/sedimentation loss leading to diffuse pollution and soil erosion, especially in periods of above-average rainfall (Eriksen, 2001; Eriksen et al., 2002; Eriksen et al., 2006; Rachuonyo and McGlone, 2007). This may not necessarily be improved with the use of mobile, compared to stationary, systems of outdoor rearing (Salomon et al., 2007). There is risk of soil compaction from heavy machinery and vehicles in wet weather, which can be alleviated by alternating roadways and field access points. These issues can be exacerbated with outdoor pigs where, unless the sows are fitted with a nose ring, the paddocks will generally become areas of bare soil due to vigorous rooting activity. In this respect, outdoor pig production has considerable potential for harm to the environment through damage to soil structure, soil erosion, and direct and diffuse pollution of ground water. Problems usually arise where marginal soils in areas of medium to high rainfall are selected. Choice of sites for outdoor pigs that are suitable for soil type, topography and rainfall, are therefore key aspects in mitigating many of these problems (see 7.1). Outdoor pigs are best suited to light free draining soils, preferably in areas of low rainfall. However, such soils are particularly susceptible to nitrate and phosphate leaching losses. A key concern is the amount of nitrate in drinking water sources, both in river waters and ground waters, but nitrogen and phosphorus can also cause the enrichment of watercourses (eutrophification) which affects the balance of organisms present in the water and its quality. Other potential pollutants from manures include heavy metals used in feed supplements, pathogens and veterinary medicines. On sloping sites for outdoor pig production, setting out paddocks so service roadways run across the site in terraced fashion rather than down the slope is an effective means of preventing a ‘water chute’ effect in periods of above-average rainfall. When this happens soil sediment and faecal contamination can be rapidly transported downhill to the nearest watercourse. Buffer strips of grass, known as bunds, and also areas of cover crops established across the bottom of an incline, can intercept water flow to prevent soil erosion through run off.


Animal welfare standards Outdoor paddocks potentially allow more opportunity for natural animal behaviour compared with the more intensive form of indoor unit. This presumes provision of wallows to help with temperature control on hot days, and opportunity to root in the soil (assuming nose rings are not used to prevent this). High animal welfare standards can only be maintained if the site has been carefully selected as being freely drained, having sufficient topsoil and not prone to flooding. It is also essential that it is stocked appropriately to enabled basic needs, such as easy access to feed, water and comfortable dry lying areas, to be provided (Farm Animal Welfare Council, 1996). In very hot weather, however, there may be an increased risk of piglet mortality when sows do not return from wallows for suckling. Predation can be a particular issue with piglets being vulnerable to attack by foxes and even large birds. Mortality can often be higher as a result of piglets being accidentally crushed by the sow in the farrowing hut as she becomes unsettled by the presence of nearby foxes.

Animal health status Pigs kept outdoors have a generally higher health status than those kept indoors (Edwards, 2005) through lower stocking densities than those used in indoor production systems. However, the increased risk of losses through exposure to wild mammals (e.g. predation of piglets by foxes), and birds and rodents pose a potential biosecurity problem. Lameness, particularly on stony or flinty soils, can occur with damage caused to sows legs and feet. Flocking of seagulls and corvids around outdoor sites also is a particular problem, with these birds sometimes having access to landfill sites and potentially food waste which could be a factor in transmission of disease. The biosecurity risk is greater in areas of the UK that have outdoor pig units close together, with wild animals acting as vectors of disease transmission. There is also risk of disease transmission through contaminated soil (Jensen et al., 2006a; Jensen et al., 2006b).

Sustainable management of land Outdoor pig production is highly compatible with many organic farming principles, although the use of nose rings is not permitted under many schemes. However, natural grazing and rooting behaviour of sows without nose rings will destroy the sward and expose bare soil, increasing the risk of soil erosion. Without nose ringing, consequences of excessive rooting activity can be best mitigated through very low stocking rates and frequent resting of paddocks. Stocking density suitable for a particular site depends on the relationship of a number of factors including soil type, rainfall and topography. 8.13. Upland beef and sheep finishing The Less Favoured Areas (LFA) account for 42% of the agricultural land in the UK, and about 65% of UK beef cows and 60% of the UK breeding ewe flocks are found in the hills and uplands (Fraser et al., 2007a). Uplands are therefore an extremely important resource for beef and sheep production. Recent changes to the EU Common Agricultural Policy (CAP) have shifted subsidy payments from a headage to a single farm payment (SFP) system, which has meant that stocking rates in the hills and uplands of the UK have declined. This potentially has important


implications on landscape value and rural employment opportunities for communities in upland areas of the UK.

Environmental benefits Grazing management in the uplands has largely led to the landscape structure that is now present. Removal of grazing animals and/or upland abandonment is likely to lead to long-term changes in plant communities, with heathland communities being replaced with scrub and eventually forest (Reed et al., 2009).

Effect on livestock output or performance Livestock output from upland areas needs careful management through the choice of appropriate breeds used and the identification of marketing opportunities for productive outputs.

Agri-environment schemes Defra is currently in the process of obtaining EC approval for its new Uplands ELS scheme, which combines existing Entry Level Stewardship (ELS) with a new uplands strand. The new Uplands ELS scheme is planned to start from 1 July 2010. The new Welsh agri-environment scheme, Glastir, also includes options for the uplands.

Rural employment Farming in the UK uplands provides substantial support for the rural economy of those areas. The use of these areas for other forms of productive agriculture are very limited.


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Review of agricultural practices and how they relate to...

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