Nutrient Requirements & Rumen Assessment

Question 1

T/F: Cows are rarely at maintenance

Answer 1

True - usually asking them to grow, lactate, gestate, etc so often times they are above maintenance

Question 2

What is maintenance?

Answer 2

Calories required to live life, but not do anything crazy
Should be able to maintain body weight

Question 3

Total energy requirement can be determined by the _______ method

Answer 3

Factorial method

Maintenance + Factors (ex. Gestation, lactation, growth, cold)

Question 4

Based on the average population, how much protein should be in the diet?

Answer 4

10% or 2lbs/day

Question 5

What determines an animal’s maintenance?

Answer 5

Weight
Sex
Type (Beef vs Dairy)

Question 6

T/F: A 1000lb angus bull, lactating jersey cow, and yearling brahma heifer all have the same maintenance requirement

Answer 6

False

Question 7

How much higher is the maintenance of a dairy cow compared to a beef breed (the standard)?

Answer 7

20%

Question 8

Within a breed, what sex will have higher maintenance requirements?

Answer 8

Bulls have 15% higher maintenance requirements than heifers and steers

More lean and less fat
Testosterone

Question 9

Lactation is _______ to ______% higher than maintenance

Answer 9

200 to 400

Question 10

Gestation is _____ to _____% higher than maintenance

Answer 10

30 to 50

Question 11

T/F: Restricting feed may decrease energy requirements.

Answer 11

True - the gut and liver (high energy using organs) adjust to intake

Question 12

What is the thermo-neutral comfort zone for cows?

Answer 12

41-77F

Need more energy if they are above or below that zone to stay warm or cool

Question 13

What happens if an animal is fed below maintenance?

Answer 13

Breakdown own body tissues

Question 14

How does a cow convert grass and hay into nutrients for metabolism?

Answer 14

Rumen microbes and enzymes break down feed into VFAs and microbial protein

Question 15

Where does glucose come from in the cow?

Answer 15

Glucose precursors go to liver for gluconeogenesis

Unlike monogastrics, if a cow is fed a candy bar, the glucose doesn’t go straight into their blood. Rumen microbes eat it all up before it has the chance. Instead the bugs break down glucose into VFAs where propionate is used as a primary glucose precursor.

Question 16

What VFA is a key glucose precursor?

Answer 16

Propionate

Question 17

Aside from propionate, what are some other substrates for gluconeogenesis?

Answer 17

Lactate, Glycerol, Amino Acids

Question 18

Acetate is used primarily as a _________ precursor

Answer 18

Fat

Question 19

What is butyrate used for?

Answer 19

Fuel for rumen and LI epithelia

Question 20

Name the three primary ketone bodies

Answer 20

B-OH Butyrate
Acetone
Acetoacetate

Question 21

T/F: A ruminant is ketotic relative to a monogastric

Answer 21

True

Question 22

What are insulin independent tissues?

Answer 22

Tissues that will snatch up glucose regardless of blood glucose levels
Ex. Fetus, mammary gland

Question 23

What is a challenge of using BCS?

Answer 23

BCS is looking at fat or lack thereof

It gets tricky when you have an extremely muscular athletic animal that has little fat. We don’t tend to give them a lower BCS score, but in reality we should

Question 24

As you go from moderate to fat, what are you adding to or losing from the body?

Answer 24

Adding subcutaneous and omental fat

Question 25

As you go from moderate to thin, what are you adding to or losing from from the body?

Answer 25

Loss of muscle mass as most subcutaneous fat is gone

Question 26

Explain how when a cow at a high BCS starts dropping BCS scores, it is initially slow but then rapidly accelerates

Answer 26

In order to meet her maintenance needs, she initially will be utilizing fat, which provides more calories per gram of body weight.

However, she will eventually run out of fat to burn and will start relying on muscle tissue.

Muscle tissue provides fewer calories per gram, so she will need to lose more muscle to reach maintenance.