90 NEBRASKA CATTLEMAN February 2025 PEERS CALVING A SEASON OF OPPORTUNITY U.S. MEAT ANIMAL RESEARCH CENTER COMMUNICATIONS Calving season is one of the annual milestones of a cow-calf operation that often serves as a time of revelation. Calving season, and its level of “success,” provides initial feedback for producers regarding the effectiveness of their selection and management decisions. Calving season, even in the best of times, is tough and truly testing; however, it is also exciting and is a time of opportunity. For producers, calving season is a reflection of past management decisions, a time to make new goals for improvement for the future, and to adjust management strategies and techniques in order to achieve those goals. Research at the U.S. Meat Animal Research Center (USMARC) in Clay Center has illustrated a potential management change for producers that may improve the efficiency of their cow herd for years to come. Researchers evaluated management decisions that impact cow stayability (or longevity) and their lifetime productivity based on the time of their first calving as a heifer. This study’s findings may have producers considering an adjustment in their heifer breeding season to improve not only the following calving season but for the lifetime of cows in their herd. Beef heifers that give birth early in their first calving season are more likely to remain in a producer’s herd and wean more pounds of calves in their productive lifetime. Many Nebraska cow-calf producers manage their heifers in this way. The team at USMARC set out to identify the effect of shortening the breeding season for beef heifers to less than two estrous cycles – resulting in an earlier calving. Heifers from the commercial Angus herd at USMARC were maintained under a short, early breeding season starting in 2015. This change in heifer management provided the opportunity for researchers to evaluate the effect that calving day as a heifer has on overall lifetime productivity if said heifers were managed and bred in a breeding season that was fewer than two estrous cycles. The performance data of these short-breeding-season heifers (heifers that had produced two or more calves) was collected and compared to heifers that were managed in a traditional-duration breeding season (heifers who had produced only one calf). The team evaluated calf birth weight, calf weaning weight and heifer stayability. The data showed that both the birth weights and weaning weights of the calves of the short-breeding-season heifers were greater than those of the heifers in the traditional-duration season. When evaluating results, it was clear that calving date as a heifer and stayability have opposing effects. Specifically, our team observed that when calving date for a first-calf heifer was later in the breeding season, her stayability in the herd decreased. So, what does this mean for a cowcalf producer? If a producer were to shorten the breeding season for heifers CONTINUED ON PAGE 92
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