Lecture quiz 05/08/23 (monday)

Question 1

what is the biological evaluation of feeds in a feeding trial?

Answer 1

-measure feed intake and the output produced (weight gain, quantity of milk or eggs)
- with measures of intake and output one can then measure the efficiency of feed utilization
- beef, swine, fish and poultry industries use feed efficiency as a benchmark for profitability
- feed to gain ratio (also called “feed conversion ratio) FCR)

Answer 2

1.9 lb of feed for every 1lb of live weight gain

Question 3

Can humans eat what livestocks eat?

Answer 3

no.

Question 4

What is the biological evaluation in a digestibility basis?

Answer 4

Digestibility = proportion of the feed that is not excreted in the feces and is therefore assumes to be absorbed by the animal, commonly expressed as a percentage
- can be calculated for dry matter, organic, and various nutrients and energy

Question 5

why do we want to know the digestibility of diets/ feedstuff?

Answer 5

depends on how it impacts the animal

• more performance, more digestible = higher feed intake

Question 6

what is apparent digestibility?

Answer 6

assumes all dry matter in the feces is from an undigested feed BUT there are substances in the feces not arising directly from the feed.

Question 7

What is the metabolic fecal products?

Answer 7

• intestinal cells and mucosa
• enzymes secreted in the digestive tract
• microbial mass

Question 8

what is true digestibility?

Answer 8

accounts for the metabolic fecal product (MFP)
- always gonna be greater than apparent digestibility

Question 9

what is MFP

Answer 9

can be quantified by measuring fecal output of fasted animals (only for non ruminants including chicken and pigs)

Question 10

what are the two types of feed energy evaluation system?

Answer 10

• TDN = total digestible nutrients
• Caloric system

Question 11

what is gross energy?

Answer 11

little direct value for evaluating feedstuff, so we use energy systems to estimate the available energy content of feeds