Nkukwana: Digestibility

Question 1

Which animal and feed factors can effect nutrient utilization?

Answer 1

• Species (ruminant vs mono-gastric)
• age
• Physiological state of the animal ( young, pregnant, lactating)
• Disease conditions
• type of feed or processing (pellet vs ground)
• Presence of anti-nutritional factors in feed.

Question 2

The potential value of a food to supply particular nutrients can be determined by____

Answer 2

Chemical analysis, after taking into account the losses due to digestion, absorbtion and metabolism.

Question 3

Define digestion

Answer 3

The proportion that is not excreted in the faeces and that is therefor, assumed to be absorbed by the animal. It is commonly expressed in terms of DM and as a coefficient or a percentage.

Question 4

What is the formula to calculate apparent digestibility ?

Answer 4

Apparent digestibility(%) = nutrient intake - nutrient loss in feces x100 / nutrient intake

Question 5

What are digestibility trials ?

Answer 5

Estimates the total amount of a specific nutrient absorbed from the gastrointestinal tract.
This is performed to measure the digestibility of a range of of feed components.

Question 6

What are the 2 measures of digestibility?

Answer 6

1) Apparent digestibility, does not account for endogenous sources like intestinal cells, enzymes and microbes
2) True digestibility, accounts for endogenous sources

Question 7

Define endogenous nutrients:

Answer 7

Fecal nutrients that originated from sloughed off intestinal cells and unused digestive enzymes of the animal.

Question 8

When doing digestibility trials, why do we prefer to use males or castrated animals?

Answer 8

It is easier te seperate faeces from the urine

Question 9

Name the 3 periods in a digestibility trial:

Answer 9

Adaptation period
Preliminary periiod
Collection period.