Missouri Bull BSE Shows 10% Fail or Deferral Rate

By Blake Jackson

“A bull breeding soundness exam (BSE) is suggested prior to each breeding season to make sure a bull is physically and reproductively sound to breed females,” says Patrick Davis, University of Missouri Extension livestock field specialist.

During the fall, MU Extension partnered with veterinarians and a pharmaceutical company to provide educational sessions and collect data during bull BSE events. Davis shares insights from these events and highlights the value of conducting a BSE.

At two veterinary clinics in southwestern Missouri, 109 bulls from 25 farms were tested. Eleven bulls from six farms either failed or were deferred, representing a 10% fail/deferral rate. Of these, five were deferred with a recommendation to retest. Bulls failing the retest would need to be culled, similar to outright failures.

These results are consistent with prior BSE data from southwestern Missouri and align with findings from other states. For example, North Dakota State data from 2014, covering 5,800 bulls, found 9% of mature bulls and 17% of yearlings failed their BSE. Conkey et al. (2019) reported a 23.71% failure rate among 1,375 bulls between 2008 and 2018, slightly higher than Missouri figures.

“There were multiple reasons for bull deferral or failure,” Davis says. Causes included no sample, lacerated penis, poor sperm morphology, and scrotal or prepuce injuries.

Some younger bulls were deferred due to underdeveloped sperm morphology, which may improve with 30-60 days of additional maturity. One bull was deferred while healing from a laceration, with the veterinarian recommending retesting in the spring.

The Alabama Cooperative Extension System notes sub-fertile bulls reduce pregnancy rates by 16% over a 63-day breeding season. They also delay conception, resulting in lighter weaning weights and reduced income.

These BSE days identified sub-fertile bulls that might have gone undetected, reinforcing Davis’s point that, “with cattle prices as they are, not doing a BSE is an expensive mistake.”

For more guidance on bull BSE and breeding management, contact your local MU Extension livestock field specialist.

Photo Credit: gettyimages-steveoehlenschlager