Midterm - Lecture 5 Flashcards
What can proteins be used for?
some ingested amino acids are used for new protean biosynthesis while others are use for glucogenesis
How is feedstuff protein determined?
kieldahl analysis
- crude protein = N X 6.25
- true protein, peptides, free amino acids, and non-protein nitrogen (urea, DNA)
What are the essential amino acids (9)?
Phenylalanine, valine, threonine, tryptophan, isoleucine, methionine, histidine, arginine, lysine, leucine
What additional essential amino acid do cats need?
taurine
What is a metabolizable protein?
the portion of the protein that gets absorbed across the small intestinal tract
How do you calculate metabolizable protein?
fed protein - protein in feces = absorbed protein
Explain the concept of a limiting amino acid.
If a diet is inadequate in any essential amino acid, protein synthesis cannot proceed beyond the rate at which that amino acid is available
Why do you need protein just for maintenance?
maintain body tissues
For pigs and chickens what is the maintenance protein requirement expressed as?
since the amino acid profiles and quantities are known, it is expressed as g of each amino acid needed
For species other than pigs and chickens, what is the maintenance protein requirement expressed as?
g ME needed
For growth, how much protein is needed?
the synthesis of protein needs to outweigh the destruction of old protein
How do you supply enough protein in most species needed for growth?
supply MP with AA profile similar to that of muscle
How does the amount of MP differ as an animal ages?
the amount of MP required per kg BW decreases as an animal becomes older and weight gain becomes more fat and less protein
What should the amino acid of MP resemble for lactation?
the amino acid profile of the milk produced
What amino acids are necessary for proper milk production?
lysine and methionine
What should the amino acid of MP resemble for pregnancy?
should match that required for growth of the fetus and uterus
When does the MP requirement during pregnancy change?
it should increase significantly only in the third of gestation when the fetus is growing rapidly
What does heavy exercise do to protein?
it increases the rate of destruction of muscle proteins
How do you need to supplement MP AA during heavy exercise?
Add MP AA profile to build muscle
What do proteins need to be broken down into to be digestible?
peptides with either 1, 2, or 3 AA long
What does heating do to protein structres?
it can unfold the tertiary structure of proteins, exposing them to digestive enzymes
What does excessive heating do to protein structures?
proteins take on globular shape and form additional cross link bonds and intestinal enzymes cannot break them down
Why do corn and soybean AA profiles compliment each other?
soybeans are high in lysine but low in methionine
corn is low in lysine but high in methionine
they make up for each others deficits
What is important in ruminant protein metabolism?
when fed properly, the rumen bacteria can make all the metabolizable protein they need