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Protein Metabolism III

Protein Metabolism III. Protein requirements and B agonists. Metabolizable Protein Model. Tissue proteins. NH 3 Blood urea Urine Amino acid pools Energy NH 3 Metabolizable Microbial protein protein Protein Protein from diet

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Protein Metabolism III

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  1. Protein Metabolism III Protein requirements and B agonists

  2. Metabolizable Protein Model Tissue proteins NH3 Blood urea Urine Amino acid pools Energy NH3 Metabolizable Microbial protein protein Protein Protein from diet Rumen Intestine Feces A B C

  3. Protein Requirements of Growing CattleChanges with Increase in Weight

  4. Protein Requirements of Growing CattleRelation to Rate of Gain

  5. Increased Protein RequirementsRuminants SituationConsequences 1. Young animals Leaner gain Fast rate of gain More total protein Leaner gain in tissues 2. Compensatory gain Greater muscle growth 3. High levels of lactation More milk protein 4. Hormone implants and bGH More protein synthesis 5. Low feed intakes Less MP from diet and microbes Need to feed higher concentrations of protein or less degradable protein

  6. 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

  7. NH3 Amino acids & Peptides VFA Amino acids Microbial Fermentation proteins CHOH VFA Bacterial ProteinSynthesis in the Rumen • Microbial protein synthesis related to: • 1. Available NH3 and amino acids (DIP) • 2. Fermentation of CHOH - Energy

  8. BCP Microbial protein synthesis • BCP (gm) = .13 TDN (gm) • Assumes • TDN is corrected for fat • RDP is adequate RDP requirement • RDP = 1.18 BCP (gm) - .2 diet CP (gm) • If RDP < 1.18 BCP – .2 diet CP, then • actual BCP (gm) = .85 (RDP+.2(CP)) (gm) • BCP is assumed to be 80% protein which has a digestibility of 80% in the small intestine

  9. 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

  10. Feed Values Beef NRC DDG 40 8530 Brome pasture 80 74 21

  11. Protein Values for Feeds DDG 120 110-5 Brome pasture 161 91 -25

  12. Programmed Feeding of Supplemental ProteinFeedlot Steers - ISU

  13. Programmed Feeding of Supplemental Protein740 lbFeedlot Steers

  14. 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

  15. Metabolizable Protein Model Tissue proteins NH3 Blood urea Urine Amino acid pools Energy NH3 Metabolizable Microbial protein protein Protein Protein from diet Rumen Intestine Feces A B C

  16. 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

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

  18. Protein Requirements of Lactating Cows

  19. 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

  20. Amino Acid Composition% Crude Protein or G/100g CP

  21. Recommendations for Feeding High RUP Byproducts to Dairy Cows

  22. Digestibility of RUPDairy NRC

  23. 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

  24. 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

  25. Limiting AA for Dairy Cattle • Lysine and methionine • Based on corn silage or alfalfa based diets • NRC (2001) suggests 7.3% of metabolizable protein as Lys, 2.5% as Met • Amino acid composition varies by protein source • Rumen protected (bypass) lysine and/or methionine can be supplemented

  26. Vyas and Erdman, 2009

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