AN SC 260 - 3.2

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AN SC 260 - 3.2
2012-10-15 01:17:01
AN SC 260

Chapter 3.2 - Amino Acids and Protein in Animal Nutrition
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  1. What are alternative N sources in monogastrics?
    D-amino acids - poory absobed (except D-methionine), can serve as N source for AA if absorbed, converted to L form

    Non-Protein Nitrogen - used for synthesis of dispensible AA, limited in monogastrics
  2. What are alternative N sources in ruminants?
    D-amino acids and Non-Protein Nitrogen - can be used effectively by ruminants (rumen miocrobes)
  3. What is an example of excessive protein intake in monogastrics?
    16, 32, 48% in pigs

    As CP intake increases, food intake, weight gain, FA synthesis, hair coat quality, and kidney/liver health decreases
  4. What is an example of excessive protein intake in ruminants?
    Ammonia toxicity
  5. What does the nutritive value of proteins depend on?
    • Dietary level
    • Absorbability
    • Metabolic usefulness
  6. Why are Maillard products great? What are they not so great?

    AA cannot be used
  7. What is a chemical score?
    Comparison of an AA profile to that of an "ideal" protein
  8. What is the "ideal" protein?
  9. What is a biological value (BV)?
    % of N absorbed which is available to for body functions
  10. What is protein efficiency ratio (PER)?
    # of g of BW gain per unit of protein consumed
  11. What is net protein utilization (NPU)?
    Efficiency of growth of animals fed a test protein relative to animals fed a protein-free diet
  12. What are blood AA patterns?
    Correlation btwn increasing amount of test AA in feed and increase of that AA in blood

  13. What is AA oxidation?
    Use of AA for protein synth vs oxidation
  14. How can the biological availability of AA be measured?
    • Microbiological assay
    • Fecal/digesta analysis
    • Growth assay
    • Plasma AA
    • Oxidation of AA
  15. Rumen microbes require nitrogen. Where do they typically get it from?
    Ammonia NH3
  16. What does ammonia deficiency in the rumen do?
    • Decreases microbial growth
    • Low intake of protein and NPN
    • Low degredation of protein in rumen
  17. What is bypass protein?
    Protein that escapes rumen digestion (still travels through the rumen but is not degraded)

    ~ 40% of true protein is bypass protein
  18. Where is bypass protein digested?
    Abomasum to yield AAs
  19. In what situations is matching protein and energy sources in ruminants important?
    High producing animals

    • Rapidly growing young ruminants
    • Peak lactation cows
  20. What has happened when ammonia overflow is reached?
    Microbes have reached capacity of converting NH3 to microbial protein

    Any increase in metabolizable E from this point on comes directly from dietary protein = bypass protein
  21. How do you increase the efficiency of protein use?
    Make protein unavailable to microbes

    • Combine NPN and protected protein
    • NPN is a cheap source of NH3 for rumen microbes
    • Microbes break down NPN instead of true protein = increased bypass protein

    Heat treat
  22. What are some ways to protect protein from microbial degradation?
    Treat with:

    • Heat
    • Heat and pressue
    • Tannins
    • Aldehydes +/- heat
    • Ionophores
    • Lipid
  23. What are the 2 forms of protein metabolism?
    • Catabolism - degradation
    • Anabolism - synthesis
  24. What role does the intestine play in AA metabolism
    • First major site of AA metabolism
    • Catabolizes 100% of glutamine, glutamate, and aspartate
  25. What role does the liver play in AA metabolism?
    Primary site of AA uptake following a meal
  26. What are 3 methods of AA catabolism? Why is the AA acid being catabolized?
    • Removal of alpha-amino group
    • Excretion of N
    • Oxidation of C-skeleton

    AA not used for synth of proteins or N-containing cmpds
  27. What are 2 ways an alpha-amino group can be removed?
    • Transamination
    • AA + alpha-keoglutarate <--> alpha-keto acid + glutamate

    • Deamination
    • Glutamate - NH3 is removed, O from a H2O molecule forms double bond in place of NH3 and regenerates alpha-ketoglutamate
  28. What are 3 types of C-skeleton oxidation?
    • Alpha-keto acids
    • alpha-keto acid + amino group <=> amino acid

    • Glucogenic AA
    • C-skeletons degraded to pyruvate or 4-/5-C intermediate in Citric Acid Cycle
    • (major source of gluconeogenesis)

    • Ketogenic AA
    • C-skeletons degraded to Acetyl-CoA or acetoacetate
  29. How are AAs synthesized?
    • Transamination reactions
    • Amino group removed from existing AA and transferred to an alpha-keto acid
    • amino acid A + alpha-keto acid <--> alpha-keto acid + amino acid B
  30. Summarize AA metabolism