# Cows need help with calving distribution

I’m intrigued by the beef cow. She’ll run you over a fence in defense of her calf. She’ll warm your heart with her motherly affection. She’ll produce to her utmost within the genetics and conditions chosen for her. And if she could converse, she would probably request that you do everything possible to help her serve you optimally.

What a smart cow! She may have already read the section on calving distribution in

the Guidelines publication of the Beef Improvement Federation, which gets at the genetic component of managing for early calves. This section contains a meaningful calving-distribution table based on a herd of 225 cows. The table shows the percentages of cows calving in 21-day periods, with the third period extended to include late calves. The percentages of cows calving in each period are as follows: First — 48, second — 31, third — 21 (includes late calves).

This table isn’t meant as an example of good distribution or bad distribution, but it does provide a basis for analysis. I have added a line to this table that gives estimated weaning weights (see accompanying table). The difference between the weights of calves born in the various periods is as follows: First to second, 65 pounds; second to third, 55 pounds. The loss from the first period to the third period is 120 pounds.

The ramifications of a broad calving spread, as you know, is a loss of potential production  —  less total weaning weight. Consider this: For every calf moved from Cycle 2 into Cycle 1, the gain would have been \$32 (late September 2005). Other moves would have produced the following results: Cycle 3 to Cycle 2, \$48; Cycle 3 to Cycle 1, \$80.

What first-cycle goal would satisfy your cow’s request? Seventy-nine percent of the cows in the BIF example calved in the first and second 21-day periods. I don’t have information on what percentage is optimal, but I suspect this one is very good. Information published by the semen marketer ABS Global Inc. shows that a 75 percent conception rate can be attained in the first 23 days of the breeding season in cows that have been time-inseminated. They also say that the conception rate can rise to 88 percent after another 21 days and to 94 percent at the 65-day point. Your environment and management situation would be factors to consider.

Whatever your goal might be, it would be wise to remember that a genetic component is imbedded in each of your improvement options. A feed wagon, vaccine syringe and vet visit will help assure proper calving condition, good health and bull soundness, but genetics will determine in the end whether you have maximized the most important element of all  —  fertility.

Unfortunately, there is no EPD (expected progeny difference) that relates specifically to fertility. Maximization of fertility requires harnessing a phenomenon of nature called heterosis. In simple terms, heterosis results from the release of performance potential normally suppressed in purebred animals through inbreeding. Suppressed performance is released through the mating of unrelated strains within a breed or through crossbreeding.

A good way to think about heterosis is like in a current TV commercial, which explains that human cholesterol originates from two sources  —  food and family. Heterosis also comes from two sources  —  Mother Nature (individual) and mother’s milk (maternal). It is the effect of individual heterosis on first-cycle conception that can improve a herd’s calving-distribution score. Highly fertile cows tend to cycle earlier in the breeding season than those of lesser fertility and are more apt to conceive when first bred.

Your answer to your cow’s request for help on first-cycle conception will be most satisfactory if you promise to do everything possible in both the physical and genetic areas of her management.

To contact Fred Knop, write Drovers or e-mail fredlyn@aol.com.

### Related Articles

No matching related articles at this time.