GOALS TO MINIMIZE THE EFFECTS OF ANIMAL PRODUCTION ON N LOADING OF THE ENVIRONMENT

• To meet the protein requirements of a specific class of animal

• To minimize total N loss from the feeding system– Feed waste– Fecal loss– Urinary loss

• Of the N excreted, have a higher proportion excreted in the feces relative to the urine.

LOSSES OF DIETARY N FED TO NONRUMINANT ANIMALSRetained LossFeed offered

Feed waste (Manure N increases 1.5%Feed consumed for each 1% increase in feed waste) Swine, % of consumed N Undigested feed 15 Fecal Endogenous secretions 8 N Nutrients absorbed

MaintenanceNutrients available for growth or egg production 50 Urinary N

Imbalance Inefficiencies (1/3 lb of protein degraded/1 lb protein gain) _______Lean growth or egg prod. 73% of consumed N is wasted

DIETARY STRATEGIES TO REDUCE N LOADING OF THE ENVIRONMENT BY NONRUMINANTS

• Reduce feed waste– Animals can be sloppy eaters– Amounts

• 5 – 6% of feed contributing 7.5% of the N in manure– May be as high as 20%

– Strategies• Feed pelleted feeds instead of mash

– Reduces feed waste by 5%• Do not overfill feeders

– Amount of feed should be limited to cover 50% of the feeder bottom (Swine)

– Fill feeder to 25% of height (Poultry)• Properly position feeders

– Swine» Utilize feeders that allow pigs to hold head straight

above feeder– Poultry

» Top of feeder should be at the base of the neck

• Reducing water waste– Problems

• Increases amounts of liquid handled in liquid manure systems• Increases problems with NH3 production, bacteria and flies in

dry litter systems– Strategies

• Fix water leaks• Swine

– Place cups under nipple waterers– Use liquid feeding systems

• Poultry– Use efficient water nipples– Adjust waterers to avoid spillage

• Increase the apparent digestibility of N– Feed highly digestible protein sources

• Protein digestibility of corn and soybeans is approx. 85%• Protein digestibility of raw soybeans is limited by trypsin inhibitor• Protein digestibility of sorghum is limited by tannins

– Feed processing• Grinding

– A uniform particle size of 700um is recommended for swine• Pelleting, expanding, or extruding

– Reduces feed waste– Provides heat

» Alters feed structure» Destroys antinutritional factors

– Must be careful to avoid overheating– Enzyme addition

• Results variable• Proteases improve gains in pigs fed whole soybeans• Fiber digesting enzymes will degrade non-starch polysaccharides

in barley and wheat– Reduces viscosity– Increases N digestibility

• Reduce endogenous N excretion– May account for 26% of total N excretion– Strategies

• Lower fiber content of the diet– Reduces sloughing of intestinal cells– Reduces bacterial fermentation in large intestine

• Heat treat soybeans to destroy trypsin inhibitor– Increases protein digestibility– Decreases protease secretion by the animal

• Precision feeding of protein– Avoid feeding protein in excess of requirements

• Example (Feeding regimes for swine giving equal performance) %CP in dietsGrower phase 17.8 17.8 16.2Finisher phase 17.1 15.4 13.5lb/pigManure N 6.3 5.8 4.9Gaseous N 2.4 2.1 1.8% reductionManure N - 9 23Gaseous N - 12 25

• Advantages– Reduces feed costs– Reduces environmental N load

• Strategies– Feed proteins for optimal gain, not necessarily maximum gain– Minimize safety margins in dietary formulation

– Balance diets for available amino acids rather than crude protein or total amino acids• In poultry, decreasing CP by 2% while maintaining amino acids

decreased N excretion by 16%

• Difficulties

– Feed composition

» Considerable variability

» Book values are unsatisfactory

» Rapid analysis is difficult and expensive

– Animal requirements

» Differ between controlled research and in the field

» Requirements vary with:

Animal genetics

Sex

Stage of growth

Environmental temperature

Balance with other nutrients

Growth promotants – Ractopamine (Paylean)

– Balance for available amino acids• Difficulties

– Current requirements are based on feeding mixtures of corn and soybeans to meet the lysine requirement» Results in overfeeding other amino acids» Requirements not well-adapted for other feed

ingredients• Strategy

– Utilize high quality protein sources or synthetic amino acids to feed an ‘ideal’ protein

– An ideal protein has all of the essential amino acids in amounts proportional to their requirements relative to lysine

– Ideal amino acid pattern for pigs, % of lysine 10-45 lb 45-110 lb 110-240 lbLysine 100 100 100Threonine 65 67 70Tryptophan 17 18 19Methionine and Cystine 60 62 65Isoleucine 60 60 60Valine 68 68 68Leucine 100 100 100Phenylalaine and Tyrosine 95 95 95Arginine 42 36 30Histidine 32 32 32

– Advantage• Predicts amino acid requirements with changing

protein:energy ratio, temperatures, and genetic capacity for lean growth

– Potential (200 lb swine) 14% CP 12% CP 10% CP Corn-soybean meal + lysine + lysine threonine tryptophan _______ _______ methionineg/dRetained N 26 26 26Fecal N 7 7 7Urinary N 34 25 17Total N excreted 41 32 24% reduction - 22 42

– Amino acids currently economically produced• Lysine• Methionine• Threonine• Tryptophan

– Separate animals by sex and feeding phase• Separate sex feeding

– Protein requirements» Intact males>Castrated males>Females

• Phase feeding– As animal grows, protein requirement decreases as a

percentage of diet– Potential of phase feeding (Swine) Feeding system Single feed Two feeds Three feedsDiet CP, % 17 (55-220 lb) 17 (55-120 lb) 17 (55-110 lb) 15 (120-230 lb)15 (110-165 lb) 12 (165-230 lb)N excretion, lb/pig/day .07 .064 .059Reduction - 8.6 15.8

– Typical number of phases» Swine 3-4» Broilers 4» Turkeys 6

– Limited by feed storage and handling

• Enhance lean growth (Swine)– Mechanism

• Increases incorporation of amino acids into protein• Reduces the effects of the maintenance requirement

– Strategies• Genetically lean pigs• Feed Ractopamine

– Sold as Paylean for pigs– Used at 18 g/T for 150 to 240 lb (5 weeks)

» Effect decreases after 4 weeks» Can’t be used longer than 90 days

– Mechanism» Shifts energy from fat deposition to muscle growth in

ham, loin, belly and shoulder– Effects

» Increases feed efficiency – 12%» Increases daily gain – 10%» Increases lean gain – 25- 37%» Decreases N excretion by 11 to 34%

– Greatest improvement in genetically lean pigs

CONSIDERATIONS TO LIMIT N EXCRETION BY RUMINANTS

• Supply adequate degradable N to meet ammonia needs of rumen microbes

• Supply adequate metabolizable protein to meet the amino acid needs of the animal for maintenance and production

• Major limitation– Proportion of total protein that is degraded or undegraded

varies in feed• Results in excess degradable protein being fed to meet

undegradable protein needs• Example A feedlot steer needs 2.5 lb of metabolizable protein per day

from a diet that supplies 1.5 lb of microbial protein per day if adequate degradable protein is fed. Therefore, the steer needs 1 lb of undegradable protein from a supplement.

Amounts of supplement needed and resulting N excess: Undegraded protein Needed CP Excess NSupplement % CP obtain 1 lb undegraded CP from supplementCorn 50 2 .16Corn silage 30 3.3 .37Alfalfa silage 20 5 .64Urea 100 ∞ ∞

STRATEGIES TO REDUCE N EXCRETION BY RUMINANTS

• Increase microbial protein production in the rumen– Maximize feed intake

• High quality feed ingredients• Properly balanced diet

– Adequate fiber– Adequate minerals– Avoid excess fat

• Proper adjustment to dietary changes– Feed highly digestible grains

• Grain species– Barley>Corn or sorghum

• Grain variety– Waxy corn > normal corn

• Grain processing– Grinding Digestibility of corn 5 – 10%– Steam-flaking Digestibility of corn 10 – 20%– Ensiling (High moisture) Digestibility of corn 10%

– Feed forages with high digestibility, but low concentration of degradable protein

Low Medium High Digestibility Corn silage Alfalfa silage Alfalfa hay Grass hay Grass or grass-legume pasture

Crude protein Corn silage Alfalfa silage Alfalfa hay Grass hay Grass or grass-legume pasture

Ruminal degradability of protein Corn silage Alfalfa silage Alfalfa hay Grass hay Grass or grass-legume pasture

– Balance other nutrients needed for microbial growth• Sulfur

– Need a 10:1 N:S ratio

• Balance supply of rumen degradable protein and undegraded protein– Supplemental protein source dependent on forage protein

degradability and energy level– If forage contains a highly degraded protein and moderate energy (like

alfalfa silage), then feed a protein supplement with low ruminal degradability.

– If forage contains a protein with low to moderate degradability and high energy level (like corn silage), then feed a protein supplement with a high ruminal degradability.

– If forage contains a low concentrations of crude protein and a moderate energy level (like corn stalks), then feed a protein supplement with a high ruminal degradability.

• Ruminal degradability of protein Ruminal degradability of protein, %Dry corn 50High moisture corn 55-60Soybean meal 65Expeller soybean meal (Soyplus) 40Corn gluten meal 25Dry corn gluten feed 70Dried distillers grains 50Urea 100

• With proper balance of RDP and RUP, dietary N can be reduced by 10 to 15% and N excretion can be reduced by 20%

– Optimal balance of degradable and undegradable protein is dependent on the animals’ body weights (growing-finishing cattle) or stage of lactation (dairy cows)• In young, light-weight cattle or dairy cows in early lactation,

metabolizable protein requirements exceed the amounts of microbial protein produced– Therefore, feed a supplement that is high in undegraded

protein• In feedlot cattle near finish or dairy cows in late

lactation, microbial protein is adequate for metabolizable protein needs– Therefore, no supplemental protein needed if degradable N

needs are met.• Implications

– Phase feed» Beef Feedlot Needs

Weight range RDP UDP ________Implications__________Light (450-650 lb) High High Supplement with high RUP sourceMed. (650-800 lb) High Mod. Supplement with high RDP source (Depending of forage protein % and degradability)Heavy (800-Finish) Mod. Mod. No supplemental protein for a corn-based diet

– ExampleYearlings fed for 132 daysDiets balance for metabolizable protein and RDP requirements Control diet Phase feeding 13.6 % CP 12.7% CP ___________ __10.1% CPLb/steerN intake 72.8 59.4N retained in carcass 7.9 7.9N excreted 64.9 51.5% of excreted N volatilized 70.9 60.7as NH3

» Lactating dairy cow Needs

Stage of lactation RDP UDP ________Implications__________Early High High Supplement with high RUP sourceMid to late High Mod. Supplement with high RDP source (Depending on forage protein % and degradability)Dry period Mod. Mod. Forage-based dry period diet likely needs no protein supplementation

» Mature beef cows (Spring-calving) Needs

Stage RDP UDP ________Implications__________Early lactation Mod. Mod. Forage-based diet usually adequateMid to late lactation Mod. Low Forage-based diet usually adequateGestation Mod. Very low Forage generally meets requirements unless low quality roughage

• Balance diets for essential amino acids by supplementing amino acids that are protected from ruminal degradation– Ruminal degradation of some amino acids are protected by

binding with minerals or poorly degraded proteins– Protected amino acids currently economically viable

• Lysine• Methionine

– Only economically viable for lactating dairy cows– Reduces N excretion by 13 to 20%

• Monitor protein status of cattle– Monitor growth or milk production– Measure milk urea nitrogen content

• Normal range, 12 -18 mg/dl

• Analyze feeds– Frequently

• Particularly with wet feeds– Sample appropriately

• Minimize feed losses– Check feed bunks daily– Clean bunks frequently– Adjust diets for feed intake to limit waste– Limit-feed large round bales to beef cows

• Feed losses from large round bales can be as high as 35%• Utilize technologies to enhance incorporation of N into meat or

milk– Implants

• Trenbolone acetate (TBA) and/or Estradiol or Zeranol• For finishing beef cattle• Increases daily gain 10-20%

– Primarily increases lean gain (improving N efficiency of N use)• Increases feed efficiency 6 – 11%

– Feed additive• Ractopamine (sold for cattle as Optiflex)• Used for finishing cattle for last 28 to 42 days• Shifts energy use for fat production to protein production• Increases daily gain by 10-12% and feed efficiency by 14-20%.

– Injection• Bovine somatotropin (sold for daily cattle as Posilac)• Injected every 2 weeks after first 9 weeks of lactation• Increases daily protein excretion in milk by 15%