lecture quiz 4: proteins Flashcards

1
Q

common commercially available synthetic antioxidants & functions

A

BHA & BHT: extend shelf life of food (prevent oxidation & rancidity that PUFA are prone to)

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2
Q

examples of natural antioxidants

A

blueberries & vitamin E

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3
Q

fat sources in animal diets

A
  • most feedstuffs (grain, forages, & some animal products) contain low levels of fat (<5%)
  • fatt suppliments (processed animal & vegitable fats) sometimes used to ↑ energy-density of animal diets
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4
Q

typical fat contents of animal diets

A
  • swine & poultry: ~5-6% (can tolerate higher levels but it would make feed sticky & cause practical issues by clogging feeding system)
  • ruminants (3-6%): too much fat (>6%) reduces fiber digestion in rumen → fat covers feed particles so microbial enzymes cannot access interferes w/ nutrient exchange in the membrane of those microbes ➞ overall reduces microbial activity so the diet cannot be digested
  • horses <5% ➞ no need for added fat, can usually meet energy requirements
  • dogs & cats vary depending on stage, envir, behaviors, as long as diet is balanced for all nutrients
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5
Q

proteins

A
  • contain C, H, O, N, & sometimes S
  • can come from anything that has DNA (encodes for proteins)
  • found in both plant & animal sources
  • made of AA (monomers)
  • AA linked by peptide bonds via condensation rxn of amino group (NH3+) + carboxyl group (-COOH)
  • in diet: typically have ≥100 AA
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6
Q

fxns of dietary protein

A
  1. provide AA for body to make its own proteins (meet requirements for AA)
  2. in excess: energy supply (as long as structural needs are met)
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7
Q

essential AA (EAA)

A

required in diet b/c cannot be synthesized by animal or in adequate amounts

  • “the tiny little monkey and violet lion in her photo”
  • threonine, tyrosine, leucine, methionine, arginine, valine, lysine, isoleucine, histidine, phenylalanine
  • cats also require taurine ➞ only found in animal tissues = 2nd reason cats considered obligate carnivores
    • most mammals can synthesize taurine from other S-containing AA (met & cys)
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8
Q

non-essential AA

A

made by animals in adequate amounts

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9
Q

D & L AA

A
  • AA can exist as isomers (specifically D or L = same chem formula but differ in chem orientation (stereochemistry) = mirror images (enantiomers)
  • L-AA exist in nature
  • animals can only use L form of AA (except Met)
  • D form = synthetic
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10
Q

limiting AA

A

EAA in a feedstuff that is in lowest amount relative to required amount

  • for essentail AA only
  • to synthesize a protein: all required AA must be present at time of synthesis ➞ if an AA is in short supply it will limit the process ∴ = limiting AA
  • when one AA is deficient, proteins can only be synthesized to the level of availablity of that AA
  • limiting AA dictates protein synthesis
  • can hve 1st, 2nd, 3rd limiting AA
  • lysine = 1st limiting AA for most animals (dogs, pigs, & many non-ruminants) in common feed
  • for poultry: because of connective tissue in feathers (that contains a lot of Met that contains S) Met is the 1st limiting AA
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11
Q

2nd reason cats considered obligate carnivores

A

cats require taurine ➞ only found in animal tissues

  • most mammals can synthesize taurine from other S-containing AA (met & cys)
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