Using Body Condition Score to Manage the Nutritional Program (Continued)

Using Body Condition Score to Manage the Nutritional Program (Continued)

April 2011

Resource: Dr. Rick Rasby, University of Nebraska - Lincoln.

Table 2 below 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.

Table 2: Nutrient Requirements of Beef Cows*
Net Energy Required Mcal/day
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
* 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

Table 3 below 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 below) 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).

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*
Mcal Net Energy for Various Cow Weights
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
* 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

 

207 Mcal
______________________________
3 lb distillers * 1.22 Mcal NEm for distillers
= 56.6 days
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