PREVIOUS ADS 520 EXAMS
ADS 520
Exam 2
May 9, 1996 Name______________________________
1. (10 pts) A group of pigs was used in a metabolism trial to
determine the energy value of a dehulled grain by-product.
The pigs ate 2,000 gm/day of the feed, and an average of
285 gm/day of feces was collected. Using a bomb
calorimeter, the GE content for the feed was determined to
be 4.3 kcal/gm and the GE of the feces was 4.2 kcal/gm.
Urine energy losses were 600 kcal/day. There were no
gaseous energy losses, but 2380 kcal of heat were lost each
day as a result of nutrient metabolism. Based on the
results of the metabolism trial, calculate the ME value
(kcal ME/kg feed) of the tested feed.
2. (6 pts) Why do we need to know the heat production of a
fasting animal to determine the NEm value of a feed?
3. (4 pts) What is the biological basis for using weight
raised to the 0.75 power when discussing energy metabolism
in animals and humans?
4. (6 pts) The Beef NRC shows that the efficiency of ME
utilization for maintenance increases as the percent
concentrate in the diet increases and the percent roughage
decreases. Based on your knowledge of energy utilization,
how would you explain this?
5. (5 pts) One promising method to increase the survival rate
of baby pigs is to include ______________ percent fat in
the diet of the sow. The way this increases survival is
__________________________________________________________
__________________________________________________________
At what point in the sow's reproductive cycle should the
fat be added to the diet?
__________________________________________________________
6. (8 pts) When the net energy values of a feed are
determined, the metabolizable energy value of the diet is
determined by __________________________________________.
The energy retained by the animals is determined by
______________________________________. The difference
between ME intake and energy retained is called
__________________________________________. The gross
energy content of protein (with units) is approximately
___________________________________.
7. (10 pts) If a high-producing dairy cow has more than 60%
concentrate (or less than 15-17% crude fiber) in her diet,
what will probably happen?
__________________________________________________________
__________________________________________________________
The dairyman can add up to _____________ percent fat to the
diet in place of some of the carbohydrate. If he adds more
than the above amount of fat, what will happen to his cows
and their milk production?
__________________________________________________________
__________________________________________________________
Two types of fat that he should not add to the diet include
a. ___________________________________________________
b. ___________________________________________________
The addition of fat to dairy diets would be expected to
(increase, decrease, not change) the total heat production
be the cow. (Circle one)
8. (3 pts) How does epinephrine cause increased heat
production by an individual?
__________________________________________________________
__________________________________________________________
9. (3 pts) Piloerection helps preserve body heat by
__________________________________________________________
10. (2 pts) The mode of heat loss when there is direct contact
between an animal and a cooler surface is called
______________________________.
11. (2 pts) The predominant mode of heat loss when the
effective environmental temperature exceeds the core body
temperature is ______________________________.
12. (4 pts) Write "increase," "decrease," or "no effect" in
the following blanks.
Compared to a cow with a fall hair coat, what effect will a
winter hair coat have on the cow's critical temperature?
__________________.
Assume a cow has a winter hair coat:
__________ A front moves through. What effect will the
wind have on the cow's critical temperature?
__________ The cow is not fed for 48 hours. What happens
to her critical temperature?
__________ What effect would a rain storm have on the
cow's critical temperature?
13. (3 pts) Under what conditions does THP = NEm?
14. (4 pts) Consider that the NEg value for corn in 1.55
Mcal/kg. We use this value as a constant for all weights
and classes of cattle. Suppose you have two groups of
steers of similar breeding and frame size. One group
weighs 700 lb. and the other weighs 1100 lb. Would the
actual NEg value of corn be greater, lower or the same for
the heavy group as compared to the lighter group. Explain
your answer.
15. (4 pts) Why does the Dairy NRC show only one value for net
energy in the tables of feed composition?
16. (5 pts) Assume you have 2 groups of steers fed either
alfalfa or barley, and both are in positive energy balance.
If you increase the ME intake of barley and alfalfa by each
steer, there will be a greater proportional increase in
energy retention from the barley than from the alfalfa.
Explain why this happens.
17. (6 pts) Use your Beef NRC. You have a group of Simmental
heifers on your farm in north Alabama that weigh an average
of 700 lb. They have ad libitum access to good quality
orchardgrass hay (early bloom) and a mineral mixture. What
is the expected ADG of the heifers? SHOW ALL WORK AND
UNITS IN AN ORGANIZED MANNER.
18. (23 pts) A comparative slaughter trial and digestibility
trial were conducted with a group of steers to determine
the energy values of a by-product feed. The trials lasted
several weeks but the data, which are summarized below,
have been calculated either on a per day basis or on a per
kilogram basis. The only thing you need to know about the
cattle is that their average weight during the comparative
slaughter trial was 360 kg. Using the knowledge you have
gained about energy metabolism, use the data to calculate
the values asked for in the questions.
Dry matter Energy
(kg/day) content
Feed 9.0 4.43 Mcal/kg
Feces 3.0 4.00 Mcal/kg
Urine 3.20 Mcal/day
Gas losses 2.00 Mcal/day
Protein and fat deposited 5.30 Mcal/day
ME content of the diet 2.52 Mcal/kg
A. (6) What is the percent digestibility of the gross energy
in the diet? Is this value the true digestibility or the
apparent digestibility? Would the other value be greater or
less than the value you have?
B. (3) Calculate the total heat production (Mcal/day) of the
steers.
C. (4) Using your knowledge of energy usage by animals,
calculate the estimated heat increment (Mcal/day) of this
feed.
D. (5) The data from the feeding trial showed that there was
no gain or loss in weight by the steers when 3.9 kg of feed
was fed. Calculate the NEm value (Mcal NEm/kg feed) of the
feed.
E. (5) Using information given or calculated in this problem,
calculate the NEg value (Mcal NEg/kg feed) of the feed.
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