STOCKTON, Missouri. – “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 cooperated with veterinarians and a pharmaceutical company to provide education and collect data during bull BSE days. Davis provides results from these events and discusses why the bull BSE pays:

During fall BSE days at two veterinary clinics in southwestern Missouri, 109 bulls were tested from 25 different farms. Eleven of the 109 bulls from six farms failed or were deferred, which is a 10% fail/deferral rate. Of the 11 bulls, the veterinarian deferred five and suggested that they be retested. If they fail the retest, they need to be culled like failed bulls. These findings are similar to data collected at previous BSE days held in southwestern Missouri. This data is also similar to North Dakota State data that summarized 5,800 bulls in 2014 and found that 9% of mature bulls and 17% of yearling bulls failed their BSE. Conkey et al. (2019) reported in Clinical Theriogenology that from 2008 to 2018 with 1,375 bull records, there was a 23.71% failure rate, which is higher than what has been seen in southwestern Missouri.

“There were multiple reasons for bull deferral or failure,” says Davis. The reasons for failure included no sample, lacerated penis, poor morphology, injured prepuce and scrotum injury. Some of the younger bulls showed underdeveloped sperm morphology. These bulls were deferred due to their potential to improve sperm morphology with an additional 30-60 days of maturity, when they may end up passing the BSE. One bull was deferred as he was healing from a lacerated penis, and the veterinarian felt that giving him a breeding season off and retesting in the spring might yield a sound bull.

The Alabama Cooperative Extension System reports that sub-fertile bulls had a 16% reduction in pregnancy rate compared to fertile bulls in a 63-day breeding season. Furthermore, the sub-fertile bulls took longer to get cows pregnant, which means younger, lighter calves at weaning. Both fates result in fewer pounds of calf to market which influences operation income and profitability. These BSE days identified sub-fertile bulls that would not have been found without testing. Davis suggests that with cattle prices as they are, not doing a BSE is an expensive mistake.

For more information about bull BSE and management before and during the breeding season, contact your local extension agent or veterinarian.