Although we hear a lot more about growth rate and beef quality and consistency these days, reproductive efficiency is easily the most important factor determining profitability of cow-calf operations. Improving reproductive efficiency is not an easy task, but I cannot imagine any other area where financial rewards are greater. There is an old saying that goes something like, "A dead calf has a very poor growth rate." I think that we can extend this concept to an "un"-conceived or unborn calf. It is impossible to profit from an animal that isn't. With this in mind, let's consider reproductive management "challenges." Furthermore, let's examine how to avoid pitfalls as we address these challenges.
Breeding Yearling Heifers
Yearling heifer management is one of the most trying aspects of cow-calf production. Reasons for breeding failure among yearling heifers usually fall into two categories: 1) the heifer is simply not old enough at breeding time or 2) the heifer is not big enough at breeding time. The age at which heifers reach puberty varies by breed. Typically, smaller breeds reach puberty earlier than larger breeds. Furthermore, breeds from Europe (Bos taurus) generally reach puberty at younger ages than Bos indicus breeds such as the Brahman. As a rule of thumb, heifers should be at least 12 months old at the beginning of the breeding season. Keep in mind this is a minimum not an average.
Average age should be 13-14 months. Heifers also need to reach a specific target weight before they reach puberty. We use a fairly simple rule to establish this target. Heifers should weigh at least two-thirds of their weight at maturity at the onset of breeding. For example, if your mature cows weigh 1200 pounds, heifers should weigh 800 pounds at the onset of breeding. Achieving adequate body weight at breeding requires careful planning. When heifers are selected at weaning, managers should conduct the following exercise.
Nutritional Management of the Cow Herd
Inadequate nutrition is also the most common cause of delayed breeding among mature cows. A reproductively efficient cow should calve every 12 months. But in order for her to accomplish this feat, she must breed back within 80 days of calving. Think about it, she will be pregnant for 285 days of the year, so there are only 80 left to recover from calving and to breed again (365 - 285 = 80). This doesn't leave much room for error. Any nutritional stress from late gestation until breeding can lengthen the postpartum interval. Cows should be in good flesh at calving and maintain this condition through the breeding season. Cows that are thin at the time of calving and those that lose body condition from calving to the onset of breeding will either breed late or end up open at the end of the season.