Bovine Nutrition and Metabolism 2

Question 1

After voluntary food intake, what is the next rate limiting step of feeding cattle?

Answer 1

Energy

Question 2

How do simple carbohydrates affaect the pH balance of the rumen?

Answer 2

Rapid fermation, creating lactic acid so there is a decrease in pH and acidosis

Question 3

Where are fats predminantly digested in the cow?

Answer 3

Abomasum/small intestine

Question 4

List three limitations of feeding fats

Answer 4

Coat fibre affecting digestion
Most decreases milk butterfat
Restrict to <6% of total diet

Question 5

What are the rule of thumb energy requirement of a cow and they milk they produce?

Answer 5

Cow - 65 MJ/day
Milk - 5 MJ/L

Question 6

What doe metabolisable energy requirements of lactation depend on?

Answer 6

Total yield
Milk composition
Diet quality

Question 7

What are the metabolisable energy requirements in pregnancy at 25, 30, 35 and 40 weeks gestation?

Answer 7

25 weeks - 5MJ/d
30 weeks - 10MJ/d
35 werks - 20 MJ/d
40 weeks - 45MJ/d

Question 8

What is conversion efficiency dependant on?

Answer 8

Use of energy
Quality of feed
Animal production level (APL)

Question 9

How does the quality of the diet effect the conversion efficiency?

Answer 9

Increased quality of diet, increases conversion efficiency

Question 10

How do you work out animal production level?

Answer 10

Total energy requirement/Energy for maintenance

Question 11

How does animal production level effect conversion efficiency?

Answer 11

Increase in APL, increase in DMI, decrease gut transit time and reduced production efficiency.

Question 12

What are the energy requirements of lactation with weight change?

Answer 12

1kg lost: ~20MJ
1kg gained: ~35MJ

Question 13

What are the energy requirements of the dry period with weight change?

Answer 13

1kg lost: ~25MJ
1kg gained: ~60MJ

Question 14

How would you work out the protein content of feed?

Answer 14

Protein ~ 16% Nitrogen
Nitrogen x 6.25 = Protein content

Question 15

What are the two types of protein bypassing the rumen?

Answer 15

Undegraded dietary protein (UDP)
Digestible undegraded protein (DUP)

Question 16

How does the rumen outflow rate affect the undegraded dietary protein?

Answer 16

Slow outflow, increases digestion and increases rumen degradable protein. Outflow approximates to volunatry food intage and

Question 17

How much more crude protein do you need extra for every litre of milk?

Answer 17

1-2g

Question 18

What is the effective rumen degradable protein?

Answer 18

The amount of rumen degradable protein actually available to rumen microbes.

Question 19

What are two problems with the metabolisable protein system?

Answer 19

Underestimates requirements (~10% fudge factor)
Individual AAs not considered