Protein Metabolism Ruminants Subjects to be covered Digestion and metabolism in the rumen Protein requirements of ruminants Models Define requirements Describe feeds Optimize production Environmental issues Prevent overfeeding nitrogen

Protein Analysis: Determine total N by Kjeldahl –All NNH 4 + –Determine as NH 3 –Total N x 6.25 = crude protein Peptide bond: NH 2 R 1 -C-C-NH OC-C=O R 2 N-C-COOH H R 3

Nitrogenous Compounds in Feeds True proteins  Polymers of amino acids (18 to 20 different amino acids) linked by peptide bonds Essential amino acids (nondispensable) –Have to be present in the diet (absorbed) –Arg Lys Trp Leu Ile Val Met Thr Phy His Nonessential amino acids (dispensable) –Synthesized in body tissues –Glu Gly Asp Pro Ala Ser Cys Tyr  Proteins Peptides Amino acids

Nitrogenous Compounds in Feeds Nonprotein nitrogen –Nitrogen not associated with protein Free amino acids, nucleic acids, amines, ammonia, nitrates, nitrites, urea Crude protein –Total nitrogen x 6.25 – Proteins on average contain 16% nitrogen

Protein Degradation in the Rumen Feed proteinsPeptides Amino acids Undegraded feed proteins Escaped feed proteins “Bypass proteins” Enzymes from protozoa and bacteria Many species of bacteria involved Bacterial enzymes are extracellular Enzymes not in cell free rumen fluid Both exopeptidase and endopeptidase activity Assumption in CNCPS: Enzymes (microorganisms) in excess – substrate limited

Factors Affecting Ruminal Protein Degradation Chemical Nature of the proteins Solubility – More soluble proteins degraded faster Some soluble proteins not extensively degraded Egg ovalbumin, serum proteins 3-dimensional structure – Affects solubility & availability Chemical bonding Disulfide bonds – Reduces degradation Physical barriers Cell walls of plants Cross linking of peptide chains – Reduces degradation Aldehydes, Tannins Feed intake Rate of passage – Time proteins remain in the rumen Feed processing Rate of passage Heat damage – Complexes with carbohydrates

Estimating Degradation of Dietary Proteins in the Rumen 1. In situ digestion Feed placed in Dacron bags suspended in the rumen Measure protein lost over time 2. Cannulated animals (rumen & duodenum) Measure protein flowing through duodenum Need to differentiate feed from microbes 3. In vitro incubation with rumen microbes Relative differences among proteins 4. In vitro digestion with fungal enzymes

Protein Degradation In situ A - All degraded B - Partly degraded Slope = degradation rate C - Not degraded Digestion time, hr Log, % N remaining

Protein Degradation DIP (RDP) = A + B[Kd/(Kd+Kp)] DIP = Degraded intake protein Kd = degradation rate, %/h Kp = passage rate, %/h UIP (RUP) = B[Kp/(Kd+Kp)] + C UIP = Undegraded intake protein

Feed Protein Fractions (CNCPS & NRC) Soluble Insoluble NPN - A Sol Proteins - B1 Insoluble - B2 Insoluble - B3 Indigestible - C Feed

Protein Fractions In Feeds Laboratory Analysis A - Soluble in buffer (borate-phosphate) and not precipitated by tungstic acid B1 - Soluble in buffer and precipitated by tungstic acid B2 - Insoluble in buffer = (Insol protein) - (protein insol in neutral detergent) B3 - Insoluble in buffer = (Insol in neutral detergent) - (Insol in acid detergent) C - Insoluble in buffer and acid detergent

Kd Values for Feed Proteins FractionKd, %/h AInfinity B1120 to 400 B23 to 16 B30.06 to 0.55 CNot degraded

Kp Values Wet forages Kp = X1 Dry forages Kp = X1 – 0.007X2 – 0.017X3 Concentrates Kp = X1 – 0.020X2 X1 = DMI, % Body Wt X2 = Concentrate, % of ration DM X3 = NDF of feedstuff, % DM

Feed Protein Acronyms NRC Publications Crude proteinTotal N x 6.25 DIP (RDP)Degraded intake protein UIP (RUP)Undegraded intake protein SolP, % CPSoluble protein NPN, % CPNonprotein nitrogen NDFIP, % CPNeutral detergent fiber insoluble protein ADFIP, % CPAcid detergent fiber insoluble protein B1, B2, B3, % hrRate constants for degradable fractions

“Bypass proteins” Proteins that are not extensively degraded in the rumen 1. Natural Corn proteins, blood proteins, feather meal 2. Modification of feed proteins to make them less degradable Heat - Browning or Maillard reaction Expeller SBM, Dried DGS, Blood meal Chemical Formaldehyde Polyphenols Tannins Alcohol + heat Usually some loss in availability of amino acids - lysine

Average Ruminal Degradation of Several Proteins Used in Level 1 Soybean meal (Solvent processed)75% Soybean meal ( Expeller processed)50% Alfalfa80% Corn proteins62% Corn gluten meal42% Corn gluten feed80% Dried distillers grains55% Blood meal20% Feather meal30% Urea 100%

Degradation of NPN Compounds Activity associated with microorganisms UreaCO NH 3 High concentrations of urease activity in the rumen Low concentrations of urea in the rumen Biuret2 CO NH 3 Low activity in the rumen NO 3 NH 3

Fate of Free Amino Acids in the Rumen 1.Amino acids not absorbed from the rumen Concentrations of free AA in the rumen very low 2.Amino acids and small peptides (up to 5 AA) transported into bacterial cells Na pumped out of cells – Uses ATP Na gradient facilitates transport of AA by a carrier 3. Utilized for synthesis of microbial proteins 4. Amino acids metabolized to provide energy

Amino Acid Degradation in the Rumen NH 3 CO 2 Amino acidsKeto acidsVFA Enzymes from microorganisms Intracellular enzymes Peptides probably hydrolyzed to amino acids and then degraded NH 3, VFA and CO 2 absorbed from rumen

Amino Acid Fermentation ValineIsobutyrate LeucineIsovalerate Isoleucine2-methybutyrate Alanine, glutamate, histidine, aspartate, glycine, serine, cystein and tryptophanpyruvate Threonine, homoserine, homocyseine and methionineKetones

Control of Amino Acid Fermentation When CHOH is ample for growth, incorporation of amino acids into protein is favored Majority of transported amino acids and peptides do not go through ammonia pool When CHOH supply is limiting growth, amino acids are fermented for energy There is an increase in amino acids going through the ammonia pool

Does Source of Carbohydrate Affect Amino Acid Fermentation? CHOH slowly fermented or with a significant lag time CHOH fermentation for growth might lag behind fermentation of AA Rapidly fermented CHOH AA fermentation and CHOH might be more closely matched Recycling of N into the rumen might offset disruptions in CHOH and AA fermentations

Amino Acid Fermenters in the Rumen High numbersLow numbers Low activity High activity Butrivibrio fibrisolvens Clostridium aminophilum Measphaera elsdenii Clostridium sticklandii Selenomonas ruminantium Peptostreptococuss anaerobius 10 9 per ml 10 7 per ml 10 to 20 NMol NH NMol NH 3 per min per min per mg protein per mg protein Monensin resistant Monensin sensitive Involved in CHOH Ferment CHOH slowly or fermentation not at all

Fate of Rumen Ammonia 1. Bacterial protein synthesis 2. Absorbed from reticulorumen and omasum NH 3 passes from rumen by diffusion into portal blood. (High concentration to low) Form of ammonia dependent on pH of rumen NH 3 + H + NH 4 + Less absorption at more acid pH 3. At pH of rumen, no NH 3 lost as gas

Fate of Absorbed Ammonia 1. Transported to liver by portal vein 2. Converted to urea via urea cycle in liver NH 3 Urea Urea cycle 3. Urea released into blood 4. If capacity of urea cycle in liver is exceeded Ammonia toxicity Over consumption of urea

Fate of Blood Urea 1. Excreted into urine 2. Recycled to digestive tract, g N/d Saliva – Related to concentration of urea in blood Sheep: 0.5 to 1.0 Cattle: 1.0 to 7.6 Diffusion into GIT Sheep: 2 to 5 Cattle: 25 to 40

Adjustments to Low Protein Intake Kidney Blood urea Urea Urine urea Urea is predominant form of N in urine Reabsorption of urea by kidney increased when ruminants fed low N diets Conserves nitrogen in the body Greater portion recycled to digestive tract Sheep fed the same diet tend to reabsorb more urea than cattle

Nitrogen Recycling - Cattle Marini et al. JAS 2003

Urea Diffusion into Rumen Rumen wall Blood urea Urea NH 3 Bacterial population 1.Total N transferred is greater when high N diets are fed. 2.Percentage of diet N transferred is greater when low N diet are fed

Urea Diffusion into Rumen Update Rumen wall Urea transporter Blood urea Urea High [NH 3 ] inhibits NH 3 Bacterial population

Sources of Nitrogen Recycled to GIT 1.Urea flowing back into digestive tract  Rumen Saliva Diffusion from blood  Lower digestive tract (large intestine, colon, cecum) Diffusion from blood Endogenous protein secretions into GIT  Mucins  Enzymes  Sloughing of tissue 2.Turnover of microbial cells in rumen & reticulum

Significance of Recycled Nitrogen Source of N for microbes when protein consumption is limited Wild species Protein intake during winter is very low Rumen deficient of nitrogen for microbial activity Slowly degraded feed proteins Recycling provides nitrogen for microbial growth Infrequent feeding of supplemental protein Programs to reduce supplemental nitrogen Difficult to make ruminants severely protein deficient

Urea Nitrogen - Cattle Marini et al. JAS 2003

Microbial Protein Synthesis End product of protein degradation is mostly NH 3 Protein synthesis Fixation of N in organic form Synthesis of amino acids Synthesis of protein(s)

Bacterial Protein Synthesis in the Rumen NH 3 Amino acids & Peptides VFAAmino acidsMicrobial Fermentationproteins CHOH VFA Microbial protein synthesis related to: 1. Available NH 3 and amino acids (DIP) 2. Fermentation of CHOH - Energy

Microbial Requirements Bacteria Nitrogen Mixed cultures NH 3 satisfies the N requirement Cross feeding can supply amino acids Pure cultures Fiber digesters require NH 3 Starch digesters require NH 3 and amino acids Peptides can be taken up by cells Branched-chain fatty acids Required by major rumen cellulolytic bacteria Energy from fermentation Need energy for synthesis of macromolecules

Amino Acid Synthesis Ammonia Fixation 1. Glutamine synthetase/glutamate synthase Glutamine synthetase Glu + NH 3 + ATPGln Glutmate synthase  -ketoglutarate + glutamine + NADPH 2 2 Glu High affinity for NH 3 - Concentrates NH 3 in cells – Uses ATP Because of N recycling this reaction may not be that important

Amino Acid Synthesis Ammonia Fixation 2. Glutamic dehydrogenase  -ketoglutarate + NH 3 + NADHGlu Low affinity for NH 3 – High concentration of enzyme in rumen bacteria – Does not use ATP Probably predominant pathway 3. Other AA can be synthesized by transamination reactions with glutamic acid Estimates of NH 3 requirements range from 5 (culture) to 20 mg/100 ml (in situ digestion)

Role of Protozoa Do not use NH 3 directly Engulf feed particles and bacteria Digest proteins Release amino acids and peptides into rumen Use amino acids for protein synthesis Protozoa engulf bacteria Protozoa lyse easily – May contribute little microbial protein to the animal

Efficiency of Microbial Growth Grams microbial N/100 g organic matter digested Ranges from 1.1 to Kind of dietForages > Grain 2. Level of feedingHigh > Low 3. Rate of passageFast > Slow 4. Turnover of microbial cells Younger cells turnover less than aging cells 5.Maintenance requirement of cells Microbes use energy to maintain cellular integrity 6.Energy spilling Dissipation of energy different from maintenance Most apparent when energy is in excess

Efficiency of Microbial Growth TDN, % feed DM G BCP/100 g TDN 813 Slow Low rumen passagepH Bacteria Low quality use energy to forages slow pump protons passage

Microbial Growth in The Rumen Nutrients available to microbes 1.DIP - NH 3, peptides, amino acids CNCPS adjusts for inadequate available N 2.Energy from the fermentation Growth rate related to Kd of CHOH Quantity of cells related to CHOH digested CNCPS assumes microbes digesting non-fiber and fiber CHOH both have a maximum yield of 50g cells/100g CHOH fermented 3.Other - branched-chain acids, minerals

Microbial Growth Computer Models 1996 Beef NRC BCP (g/d) = 0.13 (TDN, g/d) Can vary the 0.13 Lower when poor quality forages fed 1989 Dairy NRC Cattle consuming more than 40% of intake as forage: BCP g/d) = 6.25 ( TDN, kg/d)

Microbial Growth Computer Models 2001 Dairy NRC and Level 1 CNCPS BCP (g/d) = 0.13 (TDN, g/d) Correct TDN for fat added to the ration Fat does not provide energy to the bacteria Requirement for RDP (DIP) is 1.18*BCP Microbes capture 85% of available N If RDP < 1.18*BCP: BCP (g/d) = 0.85* RDP

Composition of Rumen Microorganisms

Nutritional Value of Microbial Proteins 1996 NRC for Beef Microbial protein 80% digestible in the intestine UIP 80% digestible in the intestine 2001 NRC for Dairy and Level 1 CNCPS Microbial protein 80% digestible in the intestine Digestibility of RUP (UIP) is variable in Dairy NRC UIP 80% digestible in Level 1 CNCPS

Amino Acid Composition % Crude Protein or G/100g CP TissueMilk Bact CornSoy Cell wallNon wallMean Methionine Lysine Histidine Phenylalanine Tryptophan NA Threonine Leucine Isoleucine Valine Arginine

Amino Acids in Undegraded Feed Proteins HisIslLysMet Fish meal Fish meal residue Meat & bone meal Meat & bone meal residue

Sources of Amino Acids for Host Animal 1. Microbial proteins Quantity determined by: a)Fermentability of the feed b)Quantity of feed consumed c) Nitrogen available to microorganisms 2. Undegraded feed proteins (UIP) Quantity will vary in relation to: a) Degradability of feed proteins b) Quantity of feed proteins consumed

History of Protein Systems for Ruminants ISU Metabolizable protein system Wisconsin system – When urea could be used Several European systems – Mostly MP systems 1985 NRC system – Summarized systems & Proposed a MP system Used in 1989 Dairy NRC Cornell CNCPS 1996 Beef NRC system – Mostly CNCPS system Used in ISU Brands system 2001 Dairy NRC system

NH 3 Blood urea Urine Amino acid pools Energy NH 3 Metabolizable Microbial protein protein Protein Protein from diet Rumen Intestine Feces A B C Metabolizable Protein Model Tissue proteins

Protein Metabolism of Ruminants Concept of Metabolizable Protein Metabolizable protein (MP) = Absorbed amino acids or = Digestible fraction of microbial proteins + digestible fraction of undegraded feed proteins Digestible protein (amino acids) available for metabolism Concept is similar to Metabolizable energy

FeedRumenIntestine Digestion Microbes Undegraded feed Metabolizable protein Protein Metabolism in the Rumen Less Extensively Degraded Protein

FeedRumenIntestine Digestion Microbes Undegraded feed Metabolizable protein Protein Metabolism in the Rumen Extensively Degraded Protein NH 3

Metabolizable Protein Supply to Host Animal Metabolizable protein (MP): Microorganisms – Digestible proteins Undegraded feed proteins – Digestible proteins Microorganisms g/d = 0.13 (TDN intake, g/d) (0.8) (0.8) Microbes 80% true protein that is 80% digested Feed g/d = (Feed protein) (Portion undegraded) (0.8) Feed proteins 80% digested

Absorption of Amino Acids Amino acids and small peptides absorbed by active transport (specific for groups of AA) From intestinesPortal blood Transport of amino acids into cells is similar process From bloodCells Active transport, requires energy

Utilization of Absorbed Amino Acids Via portal vein to liver Used for synthesis of proteins in liver Metabolized (deaminated) - Used for energy – Carbon for glucose Escape the liver Carried by blood to body tissues Used for synthesis of tissue proteins, milk, fetal growth, wool Metabolized - Used for energy

Requirements for Absorbed Amino Acids Metabolizable Protein (MP) Protein (amino acid) requirements 1.Maintenance 2.Growth 3.Lactation 4.Pregnancy 5.Wool

Protein Metabolism Concept of Net Protein Net protein = protein gained in tissues, milk, or fetal growth = NP Metabolizable protein is used with less than 100% efficiency Net protein = (MP - Metabolic loss) As a quantity, net protein is less than metabolizable protein

Protein Metabolism Metabolic Loss Protein synthesis and metabolism of amino acids draw from the same pool Proteins Amino acids Metabolism Metabolic loss results from continuous catabolism from amino acid pools Continuous turnover of tissue proteins adds to amino acid pools in tissues

Amino Acid (MP) Requirements Maintenance (three fractions) Protein required to support zero gain or production 1. Metabolism Metabolized Urine Milk Amino acids Feces Wool (Synthesis) GIT Scurf (Degradation) Pregnancy Tissue proteins = Endogenous urinary N 2. Proteins lost from body surface (hair, skin, secretions) = Scurf proteins 3. Proteins lost from undigested digestive secretions and fecal bacteria = Metabolic fecal N

Maintenance Requirements for Metabolizable Protein 1. Maintenance (1996 Beef NRC) 3.8 g MP/kg BW Maintenance (2001 Dairy NRC & CNCPS) Endogenous urinary N UPN = (2.75 x SBW 0.50 )/0.67 Scurf N SPN = (0.2 x SBW 0.60 )/0.67 Metabolic fecal N Dairy NRC: (DMI kg x 30) – 0.50 x ((bact MP/0.80) – (bact MP) CNCPS: 0.09 x (100 – digestible DM)

Maintenance Requirements for Metabolizable Protein

MP = X Gain 3.8 g MP/kg BW.75

Net Protein Required for Production Amino AcidsProteins Milk kg/d = (Milk yield, kg/d) (% protein in milk) Growth g/d = SWG (268 - (29.4 (RE/SWG))) SWG = Shrunk weight gain, kg/d RE = Retained energy, Mcal/d RE obtained from net energy equations.

Efficiency of Utilization of Metabolizable Protein for Deposition of Net Protein 1. Growth Beef NRC If EQEBW < 300 kg – ( x EQEBW) Otherwise Dairy NRC If EQEBW < 478 kg – ( x EQEBW) Otherwise 0.289

Efficiency of Utilization of Metabolizable Protein for Deposition of Net Protein 2. Lactation Protein in milk/0.65 (Beef NRC) Protein in milk/0.67 (Dairy NRC) 3.Pregnancy See equations in publications

Growth of Cattle – Change in Body Composition ISU experiments

Protein Requirements of Growing Cattle Changes with Increase in Weight

Example Calculation Level kg steer Gaining 1.37 kg SBW/d 10.7% protein in gain Consuming 6.8 kg feed DM 11.5% crude protein, 30% UIP 80% TDN Is this steer being fed adequate protein?

300 kg Steer MP requirement: Maintenance (Beef NRC) 3.8 ( ) = g/d Gain (1.37 (.107)/.5) (1000) = g/d Total requirement = g/d

300 kg Steer MP supplied: UIP (6.8 (.115) (.3) (.8)) 1000 = g/d Microbial (6.8 (.80) (.13) (.8) (.8)) 1000 = g/d Total MP supplied = g/d Requirement = 567.1Supply = Conclusion: Steer has adequate dietary protein

300 kg Steer Was there enough protein degraded in the rumen to furnish the nitrogen needs of the microorganisms to produce BCP? (6.8 (0.80) (0.13)) 1000 = g/d BCP (6.8 (.115) (.7))1000 = g/d DIP So this diet is short of DIP by g/d Would appear as negative ruminal N balance in CNCPS model

Consequences of Shortage of DIP Synthesis of bacterial protein is limited g rather than (.8) (.8) = g MP from microbes = g MP supplied to steer (requirement) (supply) = 29.1 g/d shortage Steer would not gain 1.37 kg/d according to model

How Can Rumen Available Nitrogen be Increased? Feed more degradable protein Usually expensive to do so unless more MP is also needed Feed nonprotein nitrogen such as urea All is degraded to NH 3. Usually cost is least Does more DIP have to be added? Models indicate yes

Supplementing Ruminal Available Nitrogen Urea ($300/ton) 159.8/2.8 = 57.1 g/d of urea could be added Urea is 280% crude protein Cost: 57.1 x = $0.0189/d Soybean meal ($200/ton) (159.8/0.75)/0.5 = 426.1/0.9 = g/d Cost: x = $0.1043/d Dry DGS ($80/ton) (159.8/0.5)/0.3 = g/d Cost: x = $0.0937/d Should: Correct urea for additional corn fed Correct DGS for corn replaced Cost corn ($2.00/bu) = $0.04/lb DM

Supplementation of Diets with Urea If inadequate DIP is available for synthesis of BCP, need to add degradable N Can add urea Urea Fermentation Potential (g urea/kg diet DM) UFP = (BCP, g/kg - DIP, g/kg)/2.8 kg = kg diet DM 2.8 = Urea is 280% crude protein + UFP: Inadequate DIP, urea will benefit - UFP: There is surplus DIP, urea of no benefit

Feed Values Beef NRC

Protein Values for Feeds

What is The Requirement for DIP? Finishing Cattle Cooper et al. JAS 2002 Fed different concentrations of urea to finishing steers Diets: Dry rolled, high moisture and steam flaked corn Measured feed intake and gain Estimated requirement for DIP (DIP as % of diet DM) Dry rolled – 6.3 High moisture – 10.0 Steam flaked – 9.5 High moisture and steam flaked corns more digestible in the rumen – Increased microbial protein production Limitations: Protein requirements change during the experiment

Programmed Feeding of Supplemental Protein Feedlot Steers - ISU ProgramCrude protein, % DM (MP – DIP, Percent of requirement) Source within period1 to 42 d43 to 84 d85 to 135 d Program I SBM-SBM-SBM 12.4 ( ) 12.4 (127 – 101) 12.4 (151 – 101) Program II Urea-Urea-Urea 11.7 (96 – 101) 11.7 (117 – 101) 11.7 (138 – 101) Program III SBM-Urea-Urea 12.4 (104 – 101) 11.7 (119 – 101) 11.7 (140 – 101) Program IV SBM-Urea-Lo Urea 12.4 (104 – 101) 11.7 (119 – 101) 10.0 (123 – 80)

Programmed Feeding of Supplemental Protein 740 lb Feedlot Steers IIIIIIIV 0 – 42 d, ADG Feed/d – 84 d, ADG Feed/d – 135 d, ADG Feed/d – 135 d, ADG Feed/d

What is The Requirement for DIP? Conclusions All of calculated DIP does not have to be satisfied when MP is being fed in excess Enough nitrogen is recycling Reduces quantity of nitrogen fed

If Diet Needs More Metabolizable Protein First consideration Can microbial protein be increased? If short of ruminal available N Add urea Provide ammonia to microorganisms If surplus of rumen available N Add fermentable feed (TDN) Provide energy to microorganisms Second consideration Supplement diet with less degradable protein

Application of Metabolizable Protein System to Feedlot Cattle Supplement protein in relation to requirement Optimize performance High performing cattle Phase feed supplemental protein Change supplement in relation to rate and composition of gain Use computer programs Supplement to minimize environmental impact

Protein Requirements of Growing Cattle Relation to Rate of Gain

Increased Protein Requirements Ruminants Situation Consequences 1. Young animalsLeaner gain Fast rate of gain More total protein Leaner gain in tissues 2. Compensatory gainGreater muscle growth 3. High levels of lactationMore milk protein 4. Hormone implants and bGH More protein synthesis 5. Low feed intakesLess MP from diet High energy dietsand microbes Need to feed higher concentrations of protein or less degradable protein

Effects of Feeding Soybean Meal Feedlot Steers Yearling steers, Revalor implants At high rates of gain, cattle respond to bypass protein.

Effects of Feeding More Urea Yearling steers, Revalor implant If DIP requirement is met, no response to feeding more urea.

Effects of Level of Soybean Meal Fed to Feedlot Steers Yearling steers, Revalor implants Greatest response to first addition of bypass protein.

Changing SBM Supplement to Urea Phase Feeding Yearling steers, Revalor implant Cattle require less protein as they approach mature finished weights Industry standard is 13.5 to 14% crude protein for finishing cattle

Nitrogen Balance - Feedlot Steers 680 to 1377 lbs Implanted and fed 14% crude protein Cattle retain 10 to 15% of dietary N during finishing.

Phase Feeding of Protein 830 lb Steers 0 to 61 days 0 to 130 days

Diets to Feed in a Phase Program Theoretical Feeding Program Crude protein: Corn 9.0%, Hay 16.0%

Rumen Degradable and Metabolizable Protein Theoretical Phase-Fed Diets Diet: I II III III III Nitrogen excreted from 10,000 head feedyard: tons

Develop Diets with Low Protein Ingredients Reduce Nitrogen Excretion Crude protein: Corn 6.0%, Hay 10.0%

Rumen Degradable and Metabolizable Protein in Phase-Fed Diets Diet: I II III IV IV Nitrogen excreted from 10,000 head feedyard: 283 tons

Response to Feeding Urea KSU Study

Response to Feeding Urea Finishing Steers KSU, lb steers fed 154 days. Diet: Dry rolled corn and 10% prairie hay.

Response to Implants and Protein 700 lb Steers --No Implant Implant No Implant -----Implant to 85 days 86 to 186 days

Effect of Implants on Nitrogen Retention Feedlot Steers

Protein Requirements of Lactating Cows

Protein Requirements of Dairy Cows Milk yield Composition of milk Body weight Maintenance Body weight change Pregnancy

Meeting Dairy Cow’s Protein Requirement Feed intake Nature of feed ingredients Fermentable energy Microbial protein synthesis in the rumen Proportion of feed protein(s) degraded Digestibility of proteins in the intestine Amino acids available for absorption Amino acid balance

Recommendations for Feeding High RUP Byproducts to Dairy Cows

Digestibility of RUP Dairy NRC

Why Limit High RUP Proteins? Lactating Cows Animal byproducts tend to reduce feed intake Palatability Fat content (Fish meal decreases milk fat) Decreased feed intake reduces microbial protein synthesis Plant byproducts may have poor amino acid balance Corn proteins deficient in lysine and tryptophan Digestibility of RUP (UIP) Might create a deficiency of RDP (DIP) Quality of RUP proteins can be variable

Why a Variable Response to RUP? Lactating Cows Protein requirements may have been met Protein might not be first limiting Cows mobilizing body proteins First limiting amino acid might not be increased Amino acid ratios of metabolizable protein Digestibility of RUP Use of RUP might cause a shortage of RDP Overestimation of degradation of other supplemental proteins