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429: Protein Nutrition

429: Protein Nutrition. Danielle Pogge . Protein . Chain of amino acids with a specific function Folding of protein determines function Enzymes, hormones, structural, etc Amino acids (20) Molecules containing an amine group Essential vs. non-essential

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429: Protein Nutrition

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  1. 429: Protein Nutrition Danielle Pogge

  2. Protein • Chain of amino acids with a specific function • Folding of protein determines function • Enzymes, hormones, structural, etc • Amino acids (20) • Molecules containing an amine group • Essential vs. non-essential • Essential = required in the diet • Lysine = 1st limiting AA; Methionine • Protein expressed as crude protein (CP) • = 6.25 x % N • Ex: DDGS, 29% CP = 4.6% N

  3. Protein in the body • Specific uses in the body: • Maintenance = primary goal • Growth • Lactation • Pregnancy (number of lambs) • Wool • Hormones and enzymes • Antibodies

  4. Protein Requirement • Ruminant Protein: • N containing feeds, NPN, endogenous • Ammonia for microbes • Amino acids for animals (SI absorption) • Dependent on: • Stage of production • Growth, gestation, lactation • Level of production • High vs. low producing • Composition of gain • Lean gain vs. fat • Ewes = 9-15% (Highest = Lactation) • Lambs = 11-20% (Highest = creep feeding) • Decrease with age

  5. Factors influencing Rumen protein degradation • Physical barriers • Plant cell walls, cross linking of peptide chains • Feed intake • Rate of passage (ingestion to excretion = ~48 h) • Fast = less degradation = more by-pass • Rumen pH • Predation of bacteria • Protozoa = engulf bacteria • Feed processing • Heat damage (increase by-pass/decrease solubility) • Maillard Reaction • SBM, DDGS, Blood Meal • Chemical damage (formaldehydes, tannins) • Coating (lipid)

  6. Types of protein: • 3 “Types” of protein: • Degraded Intake Protein (DIP) • Metabolized by microbes in rumen • Microbial Crude Protein (MCP) • Microbes themselves • Bacteria = ~50% • Protozoa = 20-60% • Contribute ammonia from protein metabolism • Undegraded Intake Protein (UIP) • “By-pass protein” • Absorbed in the small intestine • Fate of proteins in a ruminant: • Feed proteins  Peptides  Amino acids (rumen) • Undegraded, escaped AA, “by-pass” proteins (SI)

  7. Protein in Feeds: • Quality of protein is determined by the compatibility of AA profile to animals needs • New NRC (Nutrient Requirement Council) • Protein requirement based off % UIP • More UIP = lower total protein requirement

  8. Non protein nitrogen • Non-protein nitrogen (NPN) • N not associated with protein • Free AA, nucleic acids, amines, ammonia, nitrates, nitrites, urea • Ex: Urea (287% CP) • 100% degradable in the rumen • Providing N for microbes • Feeding NPN: • If inadequate DIP available for microbes • Precautions: • Less than 1/3 of total protein intake • Requires fermentable energy • Increases the S requirement Church, 1988

  9. Supplementing NPN • DIP = 8-13% Total Digestible Nutrients (TDN) • Below = benefit from NPN • Over = excrete • Ex: 100 lbs SBM = 49 lbs CP, 30 lbs DIP (49 lbs *.65 %DIP) 30 lbs DIP/87 lbs TDN = 34% of TDN

  10. Microbial Crude Protein (MCP) • Microbial sources of N: • Diet protein • NPN • Recycled N • Microbial synthesis: • Dependent on ammonia and amino acids • Energy • Balance available ammonia for bacterial growth • % of microbial protein entering SI: • Low protein diet = ~60% • High protein diet = ~40% • NPN = 100% Church, 1988

  11. Microbial Crude protein (MCP) • Microbial protein yield = 0.13 lbs MCP/lb TDN • MP yield = TDN x 0.13 • Microbial protein: ~80% protein, with digestibility of ~80% in SI • Nutritive value of microbial protein: • Increases value of low quality feed • Decreases value of high quality feed • Can survive on NPN and low amounts of recycled N

  12. Nitrogen recycling Intake Protein NPN • Routes: saliva, across rumen wall, low rumen pH • Dependent on protein in diet • Low CP = increase recycling • End of lactation dry diet = important! Metabolizable Protein Protein Microbial Protein Ammonia Urea

  13. Protein absorption • Metabolizable protein = available for metabolism • Absorbed amino acids • Microbial protein (digestible) • Undegraded protein (by-pass, digestible) • Absorption • Active transport: Intestines  Portal blood  Cells • Na dependent • Exchangers • Amino acid availability for host: • Quality, quantity, and degradation • Undegraded protein and microbial protein

  14. Protein in the body: Church, 1988

  15. Protein Nutrition • High producing animals may need a greater percent of escape/bypass protein • Ex. Ewes with triplets • Lactation (maximize production) • High quality alfalfa + corn for energy • Nutrient use: • Low quality forage (corn stalks/straw) • Supplement protein • High quality forage (alfalfa) • Often meets requirements = rarely supplement protein

  16. Managing Ewes • Management practices: • Test hays for CP values • Supplement on low quality forages (crop residue) • Sort ewes by production level • Lactation = greatest need (lose weight 2-6 weeks of lactation) • Cheap protein sources: • Soybean meal (46.5% CP) • $310 = $0.33/lb CP • DDGS (29% CP) • $200 = $0.34 • Alfalfa Hay (17% CP) • $200 = $0.58

  17. 8 7 6 5 4 3 2 1 0 .37 .52 .66 .83 .83 .93 .93 1.10 Milk Yield, protein, energy M i l k Y i e l d 2.35 TDN 1.86 TDN 1.28 TDN Protein intake

  18. Protein Nutrition • Why we care: • Protein deficiencies = reduces production • Longer days on feed, decreased milk yield, etc. • Depresses microbe function and nutrient digestion • Protein excesses: • EXPENSIVE! • Increases animal’s maintenance requirement • Environmental concerns • Increased N excretion and run off • Economics Question: • Escape protein = expensive • Is it worth it?

  19. Summary • Protein requirements: • Amino acids • Microbial protein • Energy is the limiting factor for protein utilization • Protein deficiency = decreased production • Milk, fertility, gain

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