Evaluating the Breeding Soundness of Beef Bulls

Evaluating breeding soundness of bulls is an often neglected management practice. Producers may incorrectly believe that bulls that have previously proven fertile are of sound breeding value for the rest of their lives. They may also assume that new bulls are reproductively sound simply because of some vague or implied guarantee by the seller. Unfortunately, neither assumption is correct. Bulls that do not settle their share of cows early in the breeding season contribute to reproductive inefficiency. This can be as costly as dead calves, although much less dramatic. Bulls are selected for their genetic potential to improve the cow herd. It is economically important that all bulls are fertile. An annual breeding soundness examination of each bull is the only way to predict that the producers will get their money’s worth from the bull battery. There are three periods during the year that are most logical for routine breeding soundness evaluation of the bull battery. Individual ranch situations may make one period more desirable than another. These three periods are (1) just before the breeding season, (2) immediately after the breeding season, and (3) at weaning time. The most popular time to test bulls is just before the breeding season. An evaluation at this time gives the producer the greatest assurance that the bull will be reproductively sound during the breeding season. The more time between the evaluation and the beginning of the breeding season, the less reliable the results will be as a predictor of the bull’s fertility and his ability to breed. One disadvantage of testing at this time is that it may be difficult to replace unsatisfactory animals. Evaluating bulls immediately after the breeding season allows the producer the most time to replace unsatisfactory animals. However, it is important to consider that bulls tested immediately following the breeding season may have lower semen quality due to heavy usage. Testing at weaning allows sufficient time to identify and purchase replacement sires before the next breeding season begins, but testing at this time is a less reliable indicator of the bull’s breeding soundness than testing closer to the beginning of the breeding season. A basic breeding soundness evaluation consists of: • Physical examination of the animal. • Examination of reproductive organs. • Measurement of scrotal size. • Evaluation of semen. In addition, the following tests or procedures may be included in a breeding soundness evaluation: • Mating ability: some assessment of the bull’s desire (libido) and ability to breed a female in heat (termed serving capacity). • Pelvic measurement. • Trichomoniasis testing.