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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
KENYA METHODIST UNIVERSITY
FACULTY OF EDUCATION, ARTS AND SCIENCES
PROGRAMME: DOCTOR OF PHILOSOPHY IN AGRICULTURAL AND RURAL
DEVELOPMENT
AGRI 720: ADVANCES IN ANIMAL PRODUCTION SYSTEMS
Class Assignment number ONE:
Discuss how livestock production affects biodiversity and environmental
pollution
Presented to:
Dr Mworia
By:
David Mushimiyimana (Reg: AGR-4-0304-1/2014)
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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
Contents
The Question Number One..........................................................................................................................1
Introduction.................................................................................................................................................1
Effect of Livestock Production on Biodiversity.............................................................................................2
Effect of Integrated Animal/Crop Production Systems on Water Pollution.................................................5
Effects of Different Animal Production Systems..........................................................................................6
Soil and water contaminants.......................................................................................................................7
Air Contaminants or Greenhouse Gases......................................................................................................8
(i) Volatile Fatty Acids........................................................................................................................10
(ii) Methane (CH4)...........................................................................................................................10
(iii) Gaseous ammonia.....................................................................................................................11
(iv) Dust...........................................................................................................................................13
Possible Interventions...............................................................................................................................13
Conclusion.................................................................................................................................................15
List of References......................................................................................................................................16
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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
The Question Number One
Discuss how livestock production affects biodiversity and environmental
pollution
Introduction
Thomas Malthus (1766–1834), an English economist and pioneer
demographer made a series of predictions concerning population growth
showing that while food supply increases arithmetically, population growth
increases exponentially and that the inevitable result would be hundreds of
millions of deaths by starvation in the 1960’s. Looking back today, the world
can be proud of having beaten the odds by achieving unprecedented levels
of productivity both in crop production and in livestock production.
Unfortunately, that increase in productivity came with new challenges and
agriculture is now one of the biggest contributors to environmental
degradation.
As societies continued to urbanize, plants produced food for humans and for
animals while animals provided food for humans, but only livestock recycled
nutrients back to the plants. More recently, because of the industrialization
and specialization of agriculture, the cycle that replenished the soil fertility
decreased as most producers preferred the convenience of commercial
inorganic fertilizer. In many cases, livestock production occurred as separate
specialized operations sometimes far away from plant production fields. This
change brought a major effect on the structure of livestock production, which
has focused on improving the efficiency and productivity. Economic viability
and profitability have been the primary driving forces that define the current
structure. More recently, the values of society have demanded a more
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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
sustainable environmental system from livestock production. The effect of
livestock production on rural communities also is being recognized as an
important consideration (Honeyman,1996). In this paper, it is my intention to
discuss how livestock production affects biodiversity and/or contributes to
environmental degradation by causing pollution.
Effect of Livestock Production on Biodiversity
The term “Biodiversity” is a contraction of “Biological diversity.” It means the
variability among living organisms from all sources including, among others,
terrestrial, marine and other aquatic ecosystems and the ecological
complexes of which they are a part; this includes diversity within species,
between species and of ecosystems. Biodiversity is found at different
hierarchical levels and spatial scales; e.g. genes within populations,
populations within species, species within communities, communities within
landscapes, landscapes within biomes, and biomes within the biosphere. As a
result, biodiversity encompasses variety of biological life at more than one
scale. It is not only the variety of species (both plant and animal) but also the
variety of genes within those species and the variety of ecosystems in which
the species reside. Having many different living things allows nature to
recover from change; too much biodiversity is lost, the remaining organisms
may not survive because all the living organisms depend on each other in a
stable ecosystem. Some of the ways biodiversity is lost are through habitat
destruction, introduced species, pollution, human population growth, over-
consumption etc. Unfortunately, as a result of human activities, ecosystems,
species and genetic diversity is being destroyed faster than nature can
create it. This damage threatens the ecological, economic, recreational and
cultural benefits that we receive from the Earth's living resources.
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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
Traditionally, animals and particularly ruminants were an asset to society by
converting biomass from vast grazing areas into products useful for humans,
e.g. dung, draught, milk, meat and security. However, growing human
populations cause increased and shifting demands for food and other
products. This results in the conversion of natural forests and grazing land
into arable land for crop and fodder production, thus leading to quantitative
and qualitative changes in biomass availability for human food and livestock
feed (Winrock, 1978). Where cropping is possible, it can feed more people in
terms of calories and protein than what is possible with animal production.
Apart from their inferior caloric output, compared to crops, animals are also
associated with deforestation and erosion (Durning and Brough, 1991).
However, historically, deforestation tended to start in response to the
requirement for timber for fuel and construction (Ponting, 1991). Forest was
cultivated with crops and grassland for food production through shifting
cultivation, permanent cropping or simply as a method of occupying land
(Ruthenberg, 1980). In the present day, the strong argument against
keeping of livestock is that the requirement for cropland is increasing
through expansion of grain-based beef, dairy and poultry production in the
USA, Western Europe, in peri-urban dairies of developing countries, and
recently in the Pacific Rim and China (Winrock, 1978). Combined with
changing human food patterns, this has increased the demand for crop land
relative to grazing land. As a result, even marginal grazing areas are
converted into crop land and overgrazing of the remaining areas becomes
the rule rather than the exception (Jodha, 1986). Land scarcity starts to
occur, even in pastoral areas. This upsets existing ethnic balances, and can
result in animosity between pastoralists and arable farmers who peacefully
co-existed to mutual benefit in the past (Powell and Waters-Bayer, 1985).
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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
The use of external inputs can increase the carrying capacity of some range-
land systems (Breman and De Wit, 1983). However, such external inputs are
not available or not affordable to all farmers. Hence, over exploitation (i.e.
mining) of land without the use of external inputs tends to be the result (Van
Der Pol, 1992). This threatens the sustainability of these systems, which is
defined here in simple terms as “the capacity to continue production”. Too
liberal use of external inputs, on the other hand, causes waste disposal
problems or increased political dependency on external supplies (De Haan et
al., 1997).
In general, animals are often considered to be the cause for unsustainability
in both high and low external input agricultural systems. In low external
input agricultural systems, animals are blamed for scavenging whatever is
left, while in high external input agricultural systems, the role of animals as
waste utilizers has been reverted to a role as polluters and converters of
prime resources. Rather than being an asset to sustainability, livestock
keeping has become a liability (Durning and Brough, 1991).
Livestock were components of systems with long term sustainability. For
example, the keeping of livestock was essential for survival in divergent
systems such as those of the pastoralists in Africa and on mountain ranges
unsuitable for cropping. Animals have long been essential in sustaining crop
yields in the infield–outfield systems of Western Europe and other parts of
the world, where dung and draught from wasteland grazing (outfields) was
used for crop cultivation on the infields around the homesteads. In a more
intricate way, animals helped to sustain crop yields by increasing the rate of
nutrient flows in the mixed crop–livestock systems or by allowing farmers to
include crops that fix atmospheric nitrogen, release immobilized phosphorus,
or enhance soil organic matter (Hoffland, 1991).
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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
Grazing by livestock usually follows rather than precedes deforestation
and/or cropping. In fact, animals, such as the goat, are one of the last means
of survival for large numbers of poor people on bare, exhausted, and/or arid
lands. However, in spite of the importance of animals for the poor classes of
farmers, the advocates for continued animal production on exhausted soils
should acknowledge that livestock can tip the final balance in delicate
ecosystems (Schiere and Grasman, 1997).
Effect of Integrated Animal/Crop Production Systems on Water
Pollution
Viewing manure as a valuable resource rather than as a waste product to be
disposed of is a critical first step in reestablishing the nutrient recycling
process. If properly managed, livestock production can have a positive effect
on the environment as for example livestock production and the subsequent
application of manure can counteract decreasing soil fertility and soil erosion
(Baker et al., 1990). Minimizing nutrient loss in the system by applying
manure to cropland can maintain or improve water quality in most situations.
Integrated animal/crop production systems also have a financial advantage
over specialized operations. A study of Borts et al. (2004) showed that the
diversified swine-grain farm greatly decreased fertilizer costs by using
manure, had shared implement costs, and had more stable grain
pricing/costs and thereby less risk. Flora et al. (2004) also showed that
ruminant production, based on perennial forages, could enhance water
quality and decrease nutrient losses from farms.
Unfortunately, many specialized large livestock farms often lack adequate
land base for appropriate manure application and nutrients produced in the
manure far exceed crop needs, land application alone is insufficient to
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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
handle all generated manure economically. Changing the structure of
livestock production or adopting alternative technologies to handle manure
may be necessary to maintain water quality standards.
The long-term sustainability of agriculture requires that livestock production
must not only contribute to maintaining economy, but also sustain or
improve environmental quality. Traditionally, farmers were accountable to
their communities and the land on which they lived. If their practices
resulted in harm to the environment or community, they were held
accountable. In today’s industrial agriculture, accountability is often eclipsed
by economics (Kirschenmann, 2004). The reaction is that industrialized
agriculture no longer sustains a good balance of interests and no longer
promotes trust (Anthony, 2004). Specifically, complaints include the
magnitude, intensification, cheap food mentality, and the relocation of the
decision-making power of industrial livestock production, as well as
consumer ignorance and apathy fuelled by an attitude of resignation to the
fact that “everyone else is doing it” (Lasley, 2003).
Integration of crops and livestock on-farm can enhance equity, one of the
criteria for sustainability proposed by Conway (1986). It can also affect the
export of plant nutrients to the urban centres by providing labour
opportunity and income for the country-side, as more added value remains
on farm when crop by-products are fed on farm. Integration of several forms
of production is likely to reduce pollution problems, because waste from one
subsystem can serve as a resource for another subsystem. Thus, the
waste/losses flows can be reduced due to integration.
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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
Effects of Different Animal Production Systems
The type and intensity of animal production systems is an important factor in
the extent to which animal production is detrimental to the environment.
Animal production systems can broadly be classified as grazing systems,
mixed systems and landless or industrial systems (Sere and Steinfeld, 1996).
(i) Grazing systems
Grazing systems are defined as entirely land based systems with annual
stocking rates less than 10 livestock units (LU)/ha. Grazing animals are
frequently associated with overgrazing, soil degradation and deforestation.
The environmental impact of grazing systems will first of all depend on the
stocking density and further whether the livestock has to travel to find feed
(mobile), depend on local communal pasture (sedentary) or have access to
sufficient feed within the boundaries of the farm (ranching and grassland).
Examples are extensive, pasture-based beef production and most of the
dairy production systems.
(ii) Mixed livestock systems
Mixed livestock systems are systems in which a significant part of the value
of production comes from non-livestock farming activities. Mixed livestock
systems have many opportunities for nutrient recycling. The impact of these
systems on the environment depends on the source of the feed, and thus
separate systems can be described for feed provided by communal grazing,
crop residues, cut and carry processes, produced on farm or external feed.
(iii) Industrial systems
Industrial systems have average stocking rates greater than 10 LU/ha. They
depend primarily on outside supplies of feed, energy and other inputs, and
the demand for these inputs can thus have effects on the environment in
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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
regions other than those where production occurs. Examples are poultry
production (broilers and layers), pig production, ruminant feedlot meat
production and large-scale urban dairy production. Their impact on the
environment depends both on species and on the processing of the inputs
(feed supply) and the outputs (animal products).
Soil and Water Contaminants
Most important contaminants to the soil are nitrogen as NO3, P and K. They
originate primarily from N, P and K in fertilizer and in animal manure, the
latter being a mixture of feces and urine. Although all three nutrients are
important for soil fertility, excessive levels of them in the soil cause the risk
of runoff or leaching to surface and sub-soil water, causing eutrophication.
This is particularly true for P and K. Plants have relatively high K
requirements and notably forages when used as animal feeds may contain
high amounts, much higher than the animal can efficiently use and the
surplus is excreted. Accumulation in the soil does occur but only to a limited
extent and excess K leaves the system in ground and surface water.
Although maximum values of 12 mg K/l are used for drinking water, harmful
effects are not well documented. Many foods contain much higher levels, for
instance milk contains 1500 mg K/l. Other elements that cause concern,
include Cu (used as a growth promoter in pigs, but at low levels poisonous to
sheep) and Zn (included in diets of all farm livestock).
Important water contaminants are N, P and as already indicated K. Excessive
P from runoff and erosion can fertilize surface waters and cause
microscopically small algae to multiply rapidly. The algae cloud the water
and prevent larger submerged aquatic vegetation to get enough light. The
submerged aquatic vegetation may die back, reducing the available habitat
of aquatic animals.
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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
When the algae themselves eventually die, they decompose, during which
dissolved oxygen is removed from the water, making it difficult for other
aquatic organisms to survive. For reasons of healthy drinking water on the
one hand and avoiding eutrophication with N on the other, in 1991, the EU
has accepted the nitrate directive in which member states are required to
keep the nitrate content in so-called nitrate-sensitive zones below an often
criticized value of 50 mg/l.
Air Contaminants or Greenhouse Gases
Greenhouse gases are CO2, CH4 and N2O. They are feared for their potential
to contribute to global warming. The contribution of agriculture in general
and animal production in particular to CO2 emissions are relatively small and
even in industrialized countries with highly mechanized production systems
do usually not exceed 5% (Sauerbeck, 2001).
Methane is formed by the anaerobic decay of organic matter in the
sediments of natural marshlands and rice fields. Substantial contributions
also come from ruminants, biomass burning, decay of organic matter in
landfills, fossil fuel production etc… Because of its high global warming
potential (GWP), CH4 contributes some 55% of the GWP of a dairy cow
(Johnson et al., 1997). Nitrous oxide production arises from microbial
nitrification and/or microbial or chemical denitrification in the soil. Its
emission is considered to be on average 1.25% of the amount of N applied to
that soil. Addition of nitrogen to the soil via mineral N fertilizers, animal
manure, crop residues or sewage waste generally increases the N2O
emission. Nitrous oxide emission is influenced by land use.
Air quality is a challenging environmental standard to meet because it is
difficult to quantify and control. With the emergence of larger livestock
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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
operations, there has been an increasing concentration and intensity of
odors. As livestock operations increase in size, environmental risk increases
also, and different technologies will be needed to maintain air quality
standards. Manure, once viewed as a resource to be conserved and used on
cropland, is more and more considered by many a waste disposal problem.
As a result, there is a tendency for over application of nutrients to the land,
volatilization of ammonia and hydrogen sulfide gases, and excessively large
lagoons to accommodate the wastes, all which have compromised water
supplies and air quality.
Animal husbandry is a serious source of aerial pollutants. People employed in
the farming units, as well as livestock, are submitted to a wide range of
airborne contaminants that cause respiratory irritation and sensitization
(Radon et al. 2002). These kinds of bio-aerosols are consistently emitted into
the environment by the livestock-house ventilation systems, and may
consequently affect the respiratory systems of people living next to livestock
enterprises (Intergovernmental Panel on Climate Change 2007).
(i) Volatile Fatty Acids
In contrast to monogastric animals, which obtain most of their energy from
dietary starch/sugar digested in the intestines, ruminants gain energy from
volatile fatty acids (VFA) formed by microbial fermentation of plant structural
carbohydrates, starches and proteins in the rumen. After absorption, these
VFA become the principal energy substrates for the livestock. The
predominant VFA is acetic acid which constitute50–75% of the total VFA
concentration in the rumen. Propionic acid(10–30% of total production) and
to a lesser extent butyric acid.
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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
(ii) Methane (CH4)
Methane (CH4) is the most significant source of greenhouse gas emissions
from agriculture, with 80 million tonnes of CH4 produced each year from
ruminant livestock globally (Beauchemin et al. 2008). Enteric methane is
produced through methanogenesis in the rumen and represents a loss of 6–
10% of gross energy intake for the livestock (Eckard et al.
2010).Quantification of methane emissions from livestock has gained
prominence in both government and public discussions of mitigation of
climate change and in reporting greenhouse gas emissions(Gerber et al.
2013).
Several scientists have published on the evaluation or the prediction of
pollutant emissions by ruminants, especially enteric methane (CH4) on one
hand (Sauvant et al., 2011) and urinary nitrogen (UN) output on the other
hand (Dijkstra et al. 2013). Methane is a major component (more than 50%
at the farm level) of greenhouse gas emissions while UN leads, among
others, to emissions of another greenhouse gas, nitrous oxide (Schils et al.,
2013), of ammonia in air, and of nitrates in water (Hristov et al., 2011). The
most important differences observed between trials are the influences of
energy and protein sources and the presence of some secondary metabolites
such as tannins (Jayanegara et al., 2012). Dijkstra et al. (2013) suggested
that decreasing N output could increase CH4 emission, depending on fibre
level, but their data were simulated from a mechanistic model. In fact, such
a relationship is a priori not obvious, because N intake, which is a major
driver of N output, is not known as a way for CH4 mitigation, and digestible
carbohydrates, which result in CH4 emission, are not directly related to N
excretion, except if energy is a limiting factor of microbial activity in the
rumen.
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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
(iii) Gaseous ammonia
Gaseous ammonia (NH3) is the predominant pollutant in poultry systems. It is
generated by the enzymatic decomposition of uric acid and can adversely
affect bird performance and welfare and human health, being a co-factor in
the genesis of atrophic rhinitis and bronchopneumonia (Hamilton et al.
1996).
Ammonia emission is of great environmental concern because it contributes
to soil acidification and increased N deposition in ecosystems (Pain 1998).
According to the Italian Emission Inventory of Ammonia and Greenhouse
Gases, 94% of national NH3 emissions can be attributed to agricultural
practices.
A portion of emitted NH3 reacts with acidic gases including nitric (HNO3),
hydrochloric (HCl), and sulfuric acid (H2SO4) present as aerosols, converting
the NH3 to NH4 salt particles. With significant contributions of available acid
gases from industry and transportation, their neutralization with NH3 forms
particulates that may create mist, which can be transported over long
distance before they are removed by precipitation (Asman et al., 1998).
Thus, livestock production enterprises, along with the industry and
transportation sectors, can impact very distant ecosystems.
Hatfield et al. (1993) suggested that 89 to 90% of the N inputs to anaerobic
lagoons in confined animal feeding operations were lost to the atmosphere.
These suggested NH3 emissions represented about 60% of the total feed N
input. However, Harper et al. (2005) found that only about 7.5% of N
entering into a swine production operation as feed left the area as NH3 while
another 7.3% was emitted as NH3 from the production houses and another
2% from field application of wastes to nearby. Much of the N (about 43% of
input feed) that entered the system was found to be denitrified to N2 by
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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
microbial and/or chemical denitrification. Consequently, emission factors
must be used with caution because of variability induced by geography and
meteorology, methodology for measurement, type and weight of animals, N
content of feedstuffs, housing and management, and other factors (Harper,
2005).
Intensive pig production leads to the release of environmental contaminants,
one of the most important being ammonia (NH3) (Zahn et al. 1997). Available
research data indicate that the crude protein (CP) level of the diets fed to
livestock have profound effects on NH3 emissions from excreted manure.
About 60–70% of the nitrogen (N) from the diet is excreted in the faeces and
urine (Dourmad et al. 1999). Nitrogen excreted via faeces is predominantly
incorporated in bacterial protein, which is less susceptible to rapid
decomposition, but N excreted via urine is mainly in the form of urea, which
is easily hydrolyzed and catalyzed by the urease present in feces to NH3
(van der Peet-Schwering et al. 1999). Reducing CP in pig diets can reduce N
excretion in the manure mainly due to decreased N excretion in urine (Canh
et al. 1998; Hernández et al. 2011). Several researchers have tried to
decrease NH3 by reducing dietary CP. O’Connell et al. (2006) observed
decreased NH3 emissions from slurry from pigs fed a 160 g/kg CP diet
compared with a 220 g/kg CP diet. Hayes et al. (2004) observed that NH3
emissions from pig manure can be reduced by decreasing dietary CP from
220 to 130 g/kg, from 200 to 120 g/kg and from 180 to 120 g/kg,
respectively.
(iv) Dust
Dust represents another important aerial contaminant of livestock houses,
since it is often coupled to inorganic compounds, gases, bacteria and viable
endotoxins, becoming a potentially hazardous agent (Nimmermark et al.
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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
2009). Dust can play a role in the prevalence of human respiratory diseases
as gathered from occupational health reports on farm workers in livestock
houses.
Possible Interventions
It is now widely accepted that undesired nutrient losses should be avoided or
at least kept to a minimum. This needs a combination of technical, legal and
mental interventions, the success of which will depend on the quality of
legislation and the acceptability of its implementation by stakeholders. Many
types of interventions at many sites in the production chain (soil–plant–
animal–manure) are. Important technical tools are a reduction in the use of
NPK fertilizer, nutrition and manure management.
(i) Tanging into consideration the carrying capacity of the soil
To ensure a sustainable animal production system, animal densities should
not exceed the carrying capacity of the soil. A crucial question then becomes
what the carrying capacity of the soil is. Carrying capacity is nowadays often
expressed in terms of the maximum acceptable application rates of N and P,
instead of in LU/ha or (milk) production per hectare. Livestock (LU) or animal
unit (AU) was originally defined by the FAO in 1974 on the basis of body
weight (330–500 kg), with buffaloes, horses and mules as the standard (1
AU). Later, at least in the US, this was replaced by the amount of feed
consumed and a cow was taken as standard (Ensminger et al., 1990).
(ii) Reduce external inputs
Staying within the maximum allowed limits of N and P application and losses
and maintaining a high production per hectare is only possible by limiting
inputs. Reductions in external inputs can be achieved through reduction in
fertilizer use (N, P, K) and by reducing the amount and composition of
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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
concentrates. A reduced use of inorganic fertilizers is possible without
dramatic reduction in yield (Valk et al., 2000), particularly when organic
fertilizer is applied at the right moment. The reduction will almost
automatically lead to a reduction in the loss of the greenhouse gases NH3
and N2O.
(iii) Optimizing the nutrition
Optimizing the nutrition has also been recommended as possibility to reduce
CH4 losses of ruminants. Various nutritional interventions have been
suggested to reduce CH4 production of ruminants. Examples are the use of
starch rich diets promoting the production of propionic acid, supplementation
with ionophores, the addition of fats, notably poly-unsaturated ones. Such
interventions may be feasible and effective in industrial animal production
systems, but for the vast majority of ruminants this is hardly a solution,
because the options very much depend on the production system.
(iv) Control of the composition and quality of manure
In principle, animal manure is a commodity, in many areas a valuable one,
but in surplus areas often with a negative value because of its role in
emissions to the environment. Despite this, animal manure still has a value
as fertilizer, be it that its suitability as organic fertilizer in relation to soil
quality varies. It is thought that a high carbon to nitrogen (C/N) ratio in
manure may increase its value for the soil. Hence, an increased interest in
composition and quality of manure has developed. Quality aspects are its
content of water, organic matter, N, P and K. Being a mixture of excreted
urine and fecal matter, manure is composed of end products of metabolism,
undigested dietary components, newly added endogenous components and
fermentation end products as well as biomass from endogenous
microorganisms. It was estimated (Larsen et al., 2001) that, in dairy cows,
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AGRI 720: Class Assignment number ONE, by David Mushimiyimana (Reg: AGR-4-0304-1/2014)
fecal N consisted of 16% undigested feed, 55% of microbial nature and 29%
of endogenous origin. It has also been demonstrated that in pigs the
partition of N between feces and urine can be manipulated by nutrition
without retarding protein gain (Canh et al., 1997).
Conclusion
Changes in resource/demand patterns cause changes in the behaviour of
(livestock) production systems. This implies that livestock can be essential
for the sustainability of one system in one context and detrimental for the
same or another system in a context elsewhere with other resource flows. It
is possible to identify contexts and systems where livestock can be useful for
increased sustainability and the generalized claims that livestock are
detrimental is not supported. The complexity of decision making increases
when more factors are involved, i.e. when more criteria for sustainability are
used. It is a form of experimentation and data handling that is alien to the
traditional approaches in reductionist research that separates all factors to
study only a few at a time.
Producers should be encouraged to stop making decisions based on
production efficiency and profitability alone. Instead, their decisions need to
include the impact on the environment and how they contribute to the local
community. Animal scientists also need to consider the environmental and
community effects of research and management programs.
It is important to develop production systems that integrate and respect
local community values and consider environmental impacts. There is a need
to evaluate, refine, and demonstrate these technologies and create business
systems that minimize external costs and effects on society.
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In the future, we will need to apply technologies that are consistent with the
values of society. We also need to direct research efforts to develop systems
of animal production that value and preserve natural resources. One solution
is to develop performance standards or expected outcomes for
environmental quality for the livestock industry.
List of References
Anthony, R. 2004. Ethics and animal production-two overviews. Presentation at the Sustainable Agriculture Colloquium, spring semester 2004. Dept. of Philosophy and Religious Studies. Iowa State Univ., Ames.
Asman, W.A.H.; Cellier, P.; Genermont, S.; Hutchins, N.J. and Sommer, S.G. 1998. Ammonia emission research: From emission factors to process descriptions. EUROTRAC Newsl. 20:2–10.
Borts, L.; May, G. and Lawrence, J. D. 2004. Diversified versus specialized swine and grain operations. ASL-R1959. ISU Anim. Ind. Rep. Dept. of Anim. Sci., Iowa State University, Ames.
Breman, H. and De Wit, C.T., 1983. Rangeland productivity and exploitation in the Sahel. Science 221, 1341–1347.
Canh, T.T.; Aarnink, A.J.A.; Schutte, J.B.; Sutton, A.; Langhourt, D.J. and Verstegen M.W.A. 1998. Dietary protein affects nitrogen excretion and ammonia emission from slurry of growing-finishing pigs. Livestock Production Science 56, 181–191.
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