Replacing Late Calving Beef Cows to Shorten Calving Season

There are many factors that impact profitability in cow-calf beef production. For example, retaining a female that suffers a failed pregnancy decreases the likelihood of a beef cow or heifer being profitable over her life. Several factors can cause a failed pregnancy, but retaining females that calve late within a defined calving season (days between birth of the first and last calf of an individual herd and/or multiple herds) can increase the likelihood of future failed pregnancy (Mousel et al., 2012). Late calving females get less time for uterine repair (involution) and overcoming postpartum anestrous before the next breeding season (postpartum interval), reducing the likelihood of the female becoming pregnant during the next breeding season. For example, a study found heifers that calved within the first 22 days of the defined calving season were more likely to remain in the herd longer (or increased longevity) than heifers that calved on day 23 or later (Mousel et al., 2012). A long calving season generally results in a lighter average weaning weight with a wider range of calf weights. Most cow-calf producers in the United States sell calves at weaning, and weaning typically happens when time allows regardless of calf age or weight. Therefore, calves born late in the calving season will be younger and lighter weight than early born calves. Lighter weight calves and less uniformity in calf weights can impact profitability of the herd. Calves are typically sold in lots grouped on weight ranges, and buyers commonly pay higher prices for cattle sold in larger lots (i.e., more uniform) to fill and ship truckloads more efficiently. Shortening the calving season provides an opportunity to capture price premiums from weaning weight uniformity when marketing calves (Boyer, Griffith and Pohler, 2020). However, identifying a strategy to shift to a shorter calving season can be difficult. This publication analyzes not just what happens to net returns when shortening the calving season but also what is the most profitable strategy for shortening the calving season length.