Improve Body Condition Scores
To Improve Pregnancy, Weaning and Profits
By Jason E. Sawyer, Ph.D., Texas A&M University

In a group of 100 cows, a one percent increase in pregnancy rate equals one more pregnant cow. It might be worth your while to pencil out how much that one percent increase might improve your bottom line; if you need to improve the body condition scores (BCS) of your breeding-age females to get that one percent increase; and if the more pounds of calf weaned will pay for the cost of those improvements.

Body condition and pregnancy
On average, increasing a breeding-age female’s body condition score (BCS) from 3 to 4 and from 4 to 5 make the greatest changes in pregnancy rate and weaning weight. We don’t seem to see significant improvement in production when shifting from BCS 5 to 6 (Table 1).
In our example 100-cow herd, if we improve body condition enough to increase the pregnancy rate by one percent, then we’ll get one more pregnant cow.

However, we must expect some normal herd-wide losses, such as five percent loss between pregnancy and birth, and another five percent loss from calving to weaning. On a whole-herd basis, this means our one percent pregnancy increase will provide us a .9 percent increase in weaning rate.

Let’s estimate the average weaning weight is 500 pounds. At the time of this writing, it was safe to say 500-pound calves were selling at $120 per hundred pounds.

That extra 9/10ths of a calf added to our 100-cow herd will provide an additional $540 in revenue for the herd, or $5.40 per breeding-age female.

Using $5.40 as a reasonable estimate for the increased revenue per cow due to a one percent improvement in pregnancy rate, then we see how improving body condition scores can affect income in Table 2.

Body condition and weaning
Weaning weight is influenced by calf age differences and growth rate, presumably due to changes in milk output or available forage. Cows in lower condition conceive later in the breeding season and their calves are younger at weaning.

Body condition differences should be evaluated on a pay weight basis rather than an age-adjusted basis to account for this effect.

Absolute productivity at a body condition score varies substantially due to factors such as environment, breed and timing of evaluation. Based on weighted average calf prices for May 2006, the value of 350 to 550 more pounds of weaning weight was approximately $.70 per pound.

Multiply those extra pounds by the extra value and we can determine how many dollars the extra weaning weight generates. This incorporates the slide in price with increasing pay weight (Table 2).

Add the value of the increased pregnancy rate to the value of the increased weaning weight and we have an estimate of the revenue increase from improving body condition score.

If we improve from BCS 3 to 4, we estimate $141 increased revenue per cow; from BCS 4 to 5, $117 per cow; and $55 to change from BCE 5 to 6.

If the cost to improve the condition of your breeding-age females - more or better feed - is less than the revenue increase, then improving body condition scores is a profitable decision.

How much feed will it take to improve BCS?
Table 3 shows the energy, expressed in megacalories of maintenance energy (Mcal NEm), required to change condition for different size cows, referring to their average weight at BCS 5. A megacalorie is one million calories.

If a 1,200-pound cow is observed to be BCS 6, but two months later has gone down to BCS 5, decide if you will maintain the cow at that level.

The female lost a condition score because she lost the equivalent of 266 megacalories (Mcal) of energy over the 60-day period. She is deficient by 4.4 Mcal per day.

A supplement that provides this amount of energy can correct the deficiency. Using a purchased supplement with 0.9 Mcal per pound Ñ about 82 percent total digestible nutrients (TDN) Ñ approximately 4.8 pounds per day must be fed.

As long as the cost of providing this supplement is less than $117 per head, which is the cost of the cow dropping to BCS 4, this should be a profitable decision. These comparisons can be used to budget feed expenditures and make sure that feed dollars are invested wisely.