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Table 2: Nutrient Requirements of Beef Cows*
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Net Energy Required Mcal/day
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| Month |
Maintenance |
Growth |
Lactation |
Pregnancy |
Total |
| March |
10.3 |
0 |
4.8 |
0.00 |
15 |
| April |
10.3 |
0 |
5.7 |
0.00 |
16.0 |
| May |
10.3 |
0 |
5.2 |
.01 |
15.5 |
| June |
10.3 |
0 |
4.1 |
.03 |
14.4 |
| July |
10.3 |
0 |
3.1 |
.07 |
13.5 |
| August |
10.3 |
0 |
2.2 |
.16 |
12.7 |
| September |
8.5 |
0 |
0 |
.32 |
8.8 |
| October |
8.5 |
0 |
0 |
.64 |
9.1 |
| November |
8.5 |
0 |
0 |
1.18 |
9.7 |
| December |
8.5 |
0 |
0 |
2.08 |
10.6 |
| January |
8.5 |
0 |
0 |
3.44 |
11.9 |
| February |
8.5 |
0 |
0 |
5.37 |
13.9
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*
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Assumes 1170 pound two-year-old cow calving
March 1 with average milk production. Nutrient Requirements of
Beef Cattle, 7th Revised Edition, 1996, National Academy Press,
Washington, DC
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Table 2 shows the partitioning of energy needed for
a mature cow throughout the production year. Note that maintenance
energy drops and energy for lactation ceases at weaning and that energy
for fetal growth accelerates rapidly in late gestation. This table is
only appropriate for 17.6 pounds of milk at peak production (about 50-80
days post- calving) and additional energy for maintenance and lactation
would be required for high milking cows due to larger visceral organ size.
Also of importance is the relatively low energy demand of the fetal calf
in the first and second trimester of gestation. The post-weaning period
thus becomes the logical target to increase body condition of cows because
that period (September-October-November in this case) represents the cow's
lowest nutrient demand.
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Table 3:
Energy Reserves for Different Body Sizes and Condition Scores of Cows.
Amount of Energy Needed to Move to the Next Higher Body Condition Score.
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Mcal Net Energy for Various Cow Weights
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| BCS |
1100 |
1200 |
1300 |
1400 |
| 2 | 139 |
151 | 164 |
177 |
| 3 | 157 |
172 | 186 |
200 |
| 4 | 180 |
196 | 212 |
229 |
| 5 | 207 |
226 | 245 |
264 |
| 6 | 242 |
264 | 286 |
308 |
| 7 | 285 |
311 | 337 |
363 |
| 8 | 342 |
373 | 405 |
436 |
| 9 | 418 |
456 | 494 |
532
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| * |
The numbers in the body of the table
represent the energy required to move a cow from the next
lower BCS to the present one. Nutrient Requirements of Beef
Cattle, 7th Revised Edition, 1996. National Academy Press,
Washington, DC
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Table 3 shows the amount of energy in megacalories
(Mcal = one million calories) required to change body condition of cows.
For example, if the goal was to increase the body condition of an 1100
pound cow from a BCS 4 to a BCS 5, the cow would need a total of 207 Mcal
of energy beyond her daily maintenance needs found in Table 2. This 207
Mcal of additional energy could be supplied by an energy dense feedstuff
such as dried distillers grains (Table 4) which has 1.22 Mcal of NE per
pound. If 3 pounds of distillers grains were fed, it would take about 57
days to elevate the cow's body condition from a BCS 4 to a BCS 5. The cow
would have to gain about 1.32 pounds per day to achieve this change in body
condition (75 pounds divided by 57 days = 1.32 pounds per day).
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207 Mcal |
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= 56.6 days |
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3 lb distillers * 1.22 Mcal NEm
for distillers |
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