Name _____________________
Animal Science 320
Fall, 2012
Problem Set 2
Due January 30, 2013
1. You are managing horses for a farm and were approached by a feed company trying to sell
the farm a “superior” horse diet. You would like prove to the farm owner that this new diet
for the horses is better so you conduct a digestibility trial.
Assumptions: Horse consumes 100% of both diets = 18 Pounds daily (as fed)
Feedstuff
Current diet
Test Diet
DM, %
87
87
Component
Fecal output (wet), Lb/day
Fecal dry matter, %
Fecal crude protein, % DM
Fecal fiber, % DM
Fecal NFE, % DM
Fecal EE, % DM
CP
13.1
14.2
Ash
7.5
6.0
% of DM
CF
32.0
28.7
Current Diet
16.3
38.0
10.5
45.0
24.0
3.5
EE
3.8
4.3
NFE
43.6
46.8
Test Diet
14.5
40.0
9.8
39.0
26.5
2.5
Diet Data
Diet
DM intake, Lb/day
CP intake Lb/day
Fiber intake, Lb
day
NFE intake Lb/day
EE intake, Lb/day
Fecal DM output,
Lb/day
Fecal CP output,
Lb/day
Fecal fiber output,
Lb/day
Fecal NFE output,
Lb/day
Fecal EE output,
Lb/day
Current Diet
Test Diet
Fecal Data
Diet
Current Diet
Test Diet
Digestibility Data
Dry matter
Diet
digestibility, %
Protein
digestibility, %
Fiber
digestibility, %
Current diet
Test diet
What is your defense for the farm owner regarding the two diets?
NFE
digestibility, %
EE
digestibility,
%
2. Based on the horse example above, can you argue the diet change from a financial standpoint
when the test diet cost is $0.40/Lb and the regular farm diet is $0.30/Lb (think TDN and
show work).
a) Calculate TDN for each diet (show work).
TDN Current Diet
TDN Test Diet
(%)
b) Based on TDN, how much less dry matter intake would a horse theoretically be
consuming on the test diet?
c) How much would it cost the farm per year to feed 6 horses each diet based on
maintaining digestibility of the diets (assuming all 6 horses consumed 18 Lb as fed
daily)?
3. A producer has the choice of purchasing any of the hays below for feeding to 88 lb
replacement ewe lambs. If these ewes require 2.0 lb of TDN daily, will the ewes meet their
needs from each of the hays given the information below? Show calculations.
Composition:
Hay
Alfalfa – grass
hay
Bluegrass
Red clover hay
DM, %
91
CP
16
Ash
7
% of DM
CF
33
EE
2.5
NFE
41.5
90
88
10
22.5
6
9
28
21
3
4
53
43.5
Digestion coefficients:
Hay
Alfalfa – grass hay
Bluegrass
Red clover hay
CP
77
73
81
Ash
80
80
80
Digestion coefficient, %
CF
54
56
62
EE
53
55
56
NFE
73
70
77
Digestible nutrients
Hay
DP
Alfalfa – grass
hay
Bluegrass
Red clover hay
Show calculation of TDN
DAsh
Digestible nutrients,% of DM
DCF
DEE
DNFE
Total
digestible
nutrients
Adequacy of hay for TDN for gestating ewe:
TDN
Hay
DMI, lb/day
Alfalfa – grass hay
Bluegrass
Red clover hay
3.1
2.8
2.8
% of DM
Lb/day
Adequate (Yes or
No)
4. Using Table 3.2b Composition of Feeds-Energy Values and Table 2-4 NE Requirements for
Growing and Finishing Heifers (Medium-frame) both from the text, calculate the daily gain
of 700 Lb medium-frame beef heifers consuming 19 Lb as-fed of the following rations (A
and B). Using that daily gain, calculate the number of days and total feed cost to finish these
heifers to a weight of 950 lb.
A.
Ration A (Feed cost=$0.1000/lb as-fed)
Ingredient
IFN
% as-fed
Maize, dent yellow, grain
4-02-935
83
Maize, Silage, well-eared
3-02-823
15
Urea
5-05-070
1
Mineral and Vitamin
No number
1
Supplement
(100% DM, 0 NE)
Ingredient
% of
diet,
as-fed
Lb,
as-fed
DM,
% (from
Lb
DM
Kg
DM
Table
3.2b)
NEm
Mcal/Kg Mcal
NEg
Mcal/Kg Mcal
(from Table
3.2b)
(from Table
3.2b)
Corn grain
83.0
88.0
2.16
1.48
Corn silage
15.0
34.1
1.63
1.03
Urea
1.0
97.0
0
0
Mineral
and
Vitamin
Supplement
Total
1.0
100
0
0
100
19
Mcal/Kg Diet DM
NEm requirement, Mcal/day (Find from Table 2-4, page 106)
Feed DM used for maintenance, Kg/day
Total DM intake, Kg/day (From previous page calculations)
Feed remaining for gain, Kg/day
NEg available for gain, Mcal/day
Predicted daily gain, Lb/day
Days to gain 250 Lb to finish
Feed cost to gain 250 Lb to finish, $
5.80
B.
Ration B (Feed cost = $0.0950 as-fed)
Ingredient
IFN
Maize, dent yellow, grain
4-02-935
Maize, Distillers grains with
5-02-843
solubles, dehydrate
Maize, Silage, well-eared
3-02-823
Mineral and Vitamin
No number
Supplement
(100% DM, 0 NE)
Ingredient
Corn grain
% of
diet,
as-fed
Lb,
as-fed
DM,
% (Find
Lb
DM
Kg
DM
in Table
3.2b)
% as-fed
49
35
15
1
NEm
Mcal/Kg Mcal
NEg
Mcal/Kg Mcal
(Find in
Table 3.2b)
(Find in
Table 3.2b)
49.0
88.0
2.16
1.48
Corn
35.0
Distillers
Grains with
Solubles
Corn silage 15.0
34.1
1.63
1.03
Mineral
1.0
and
Vitamin
Supplement
Total
100
19
Mcal/kg Diet DM
NEm requirement, Mcal/day (From Table 2-4)
Feed DM used for maintenance, Kg/day
Total DM intake, Kg/day (From previous page calculations)
Feed remaining for gain, Kg/day
NEg available for gain, Mcal/day
Predicted daily gain, Lb/day
Days to gain 250 Lb to finish
Feed cost to gain 250 Lb to finish, $
5. Using Table 3.2b Composition of Feeds-Energy Values and Table 2-4 NE Requirements
for Growing and Finishing Heifers (Medium-frame), calculate how much of Ration A
would have to be consumed to have an 500 Lb heifer gain 3.0 lb per day and the feed
cost/100 Lb of gain assuming that the feed cost=$0.1000/lb as-fed)
NEm
NEg
Mcal/kg Diet DM
NE Requirements for 500 Lb heifers, Mcal/day
(Table 2-4))
Feed required to meet NEm and NEg requirements, Kg DM
Total feed required, Kg DM/day
Total feed required, Lb DM/day
Lb DMI/Lb BW gain
Lb as-fed feed/Lb BW gain
Given Dry matter of diet = 80.1%
Feed cost/100 Lb BW gain
6. You ran calorimetry on a dog food and the gross energy was 5,500 cal/g (dry matter basis).
After metabolism trials, the fecal energy was 535 cal/g and urine energy was 160 cal/g.
Dry matter of this food is 90.5%
1 cup of food = 125 grams
Digestible energy (DMB, cal/g)
Digestible energy (DMB, kcal/g)
Metabolizable energy (DMB, cal/g)
Metabolizable energy (DMB, kcal/g)
ME per cup (DMB, kcal/cup)
ME per cup (As Fed, kcal/cup) *
* This value would appear on the food label for consumers