Midterm - Lecture 5

Question 1

What can proteins be used for?

Answer 1

some ingested amino acids are used for new protean biosynthesis while others are use for glucogenesis

Question 2

How is feedstuff protein determined?

Answer 2

kieldahl analysis

• crude protein = N X 6.25
• true protein, peptides, free amino acids, and non-protein nitrogen (urea, DNA)

Question 3

What are the essential amino acids (9)?

Answer 3

Phenylalanine, valine, threonine, tryptophan, isoleucine, methionine, histidine, arginine, lysine, leucine

Question 4

What additional essential amino acid do cats need?

Answer 4

taurine

Question 5

What is a metabolizable protein?

Answer 5

the portion of the protein that gets absorbed across the small intestinal tract

Question 6

How do you calculate metabolizable protein?

Answer 6

fed protein - protein in feces = absorbed protein

Question 7

Explain the concept of a limiting amino acid.

Answer 7

If a diet is inadequate in any essential amino acid, protein synthesis cannot proceed beyond the rate at which that amino acid is available

Question 8

Why do you need protein just for maintenance?

Answer 8

maintain body tissues

Question 9

For pigs and chickens what is the maintenance protein requirement expressed as?

Answer 9

since the amino acid profiles and quantities are known, it is expressed as g of each amino acid needed

Question 10

For species other than pigs and chickens, what is the maintenance protein requirement expressed as?

Answer 10

g ME needed

Question 11

For growth, how much protein is needed?

Answer 11

the synthesis of protein needs to outweigh the destruction of old protein

Question 12

How do you supply enough protein in most species needed for growth?

Answer 12

supply MP with AA profile similar to that of muscle

Question 13

How does the amount of MP differ as an animal ages?

Answer 13

the amount of MP required per kg BW decreases as an animal becomes older and weight gain becomes more fat and less protein

Question 14

What should the amino acid of MP resemble for lactation?

Answer 14

the amino acid profile of the milk produced

Question 15

What amino acids are necessary for proper milk production?

Answer 15

lysine and methionine

Question 16

What should the amino acid of MP resemble for pregnancy?

Answer 16

should match that required for growth of the fetus and uterus

Question 17

When does the MP requirement during pregnancy change?

Answer 17

it should increase significantly only in the third of gestation when the fetus is growing rapidly

Question 18

What does heavy exercise do to protein?

Answer 18

it increases the rate of destruction of muscle proteins

Question 19

How do you need to supplement MP AA during heavy exercise?

Answer 19

Add MP AA profile to build muscle

Question 20

What do proteins need to be broken down into to be digestible?

Answer 20

peptides with either 1, 2, or 3 AA long

Question 21

What does heating do to protein structres?

Answer 21

it can unfold the tertiary structure of proteins, exposing them to digestive enzymes

Question 22

What does excessive heating do to protein structures?

Answer 22

proteins take on globular shape and form additional cross link bonds and intestinal enzymes cannot break them down

Question 23

Why do corn and soybean AA profiles compliment each other?

Answer 23

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

Question 24

What is important in ruminant protein metabolism?

Answer 24

when fed properly, the rumen bacteria can make all the metabolizable protein they need