Farming Facts: Converting from year round calving

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By Bryce Roberts

Maintaining a controlled breeding and calving season can be one of the most important management tools for cow-calf producers. Uniform, heavier and more valuable calves are key reasons to keep the breeding season short. Plus, more efficient cow supplementation and cow herd health programs are products of a short breeding season. However, you shouldn’t convert from yearlong breeding to a shortened breeding season without a lot of planning.
A system for converting from year-round to a 75-day controlled calving season over a period of two years presents less loss and fewer problems than to trying to convert in one year. Here are some suggestions for getting on a controlled breeding system:
1. Determine the ideal time of year and the length of your new calving season. For example, decide you want your cows to calve from Feb. 15 to April 30 (74 days).
2. Determine the reproductive status of each cow in your herd. First, go to your record book to determine the last date each cow calved. If you don’t keep records, try to match the cows and calves up and estimate their age.
3. Based on the reproductive status of your herd, determine if you would like one or two controlled calving seasons.
4. Build a good strong bull pen or well-fenced bull pasture. You may need an electric fence in addition to the regular fence.
5. Remove your bulls from the herd. Select the removal date to coincide with an approximate 120-day season for your spring-calving cows.
6. Sixty days after removing the bulls from the herd (or at a convenient time near this date), pregnancy check all cows and cull all non-pregnant, dry, breeding-age females that have been running with the bull and all non-pregnant cows with calves 5 months of age or older. Your fall-calving cows have likely either calved or are very close to calving.
7. You may want to consider starting the breeding season of your replacement heifers 20 to 30 days ahead of the final breeding date for your herd. Most extended calving seasons are the result of failure of young cows to rebreed in a timely fashion. The additional 20 to 30 days enhances the opportunity for these young cows to rebreed next season. So, if you have spring-calving cows, replacement heifer breeding season would start around April 10, and these females would begin calving around Jan. 20. This may be a bit early for calving, and you might experience 1 to 2 percent higher calf loss. Financially, 1 to 2 percent loss is easier to swallow than a 25 percent decrease in pregnancy rate the following year.
8. The second year, follow the same system as outlined above except remove the bull on the week of July 20. If you have fall and spring-calving cows, then put the bull in for the fall cows around Nov. 20 and remove him around Jan. 20.
Feel free to contact me at your Spencer County Cooperative Extension Service at 477-2217 or you can email me at broberts@uky.edu. You can visit the Spencer County Extension Services’ website at www.spencerextension.com.
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