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)
2
Q
examples of natural antioxidants
A
blueberries & vitamin E
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
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
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
6
Q
fxns of dietary protein
A
- provide AA for body to make its own proteins (meet requirements for AA)
- in excess: energy supply (as long as structural needs are met)
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)
8
Q
non-essential AA
A
made by animals in adequate amounts
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
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
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)