Importance of Bull Health for Calf Production Success

By Blake Jackson

“Calf production is perhaps the most important metric that supports the existence of the cattle industry, making bull health and productivity incredibly important,” says Ian McGregor, University of Missouri Extension livestock field specialist.

The Bull Breeding Soundness Exam (BSE) Days aim to evaluate the overall health, physical soundness, and reproductive ability of bulls, while also educating producers on effective bull management for a successful breeding season, McGregor explained.

This spring, during the Southwest Missouri BSE Days, MU Extension collaborated with seven veterinary clinics to work with 43 farms.

A total of 152 bulls underwent BSEs. Of those, 12 bulls either failed or were deferred for a future retest by a veterinarian, reflecting an 8% failure or deferral rate consistent with past years.

Causes of failure included poor semen quality, absence of semen, penile injuries, penile warts, and scrotal frostbite. Bulls that fail can be replaced in time for breeding season, while deferred bulls can be re-evaluated in 60 days.

“Body condition score (BCS) and energy status of a bull is an important factor for the bull to be able to breed females and maintain adequate semen quality,” McGregor says.

The target BCS is 5 for both bulls and cows; however, a BCS of 6 is preferable for bulls entering the breeding season due to its higher energy demands. In this spring’s assessments, 47 bulls scored 4 or lower.

The timing early spring, before fresh forage is widely available makes it difficult for bulls to maintain or gain condition, especially when relying on dwindling feed supplies and already engaging in breeding activities.

“Bulls spend a lot of time on their feet, running around trying to mount females during the breeding season,” says McGregor. “If a bull has poor leg or foot structure, it can make the breeding effort uncomfortable, and the bull may be less productive.”

This year’s exams also included evaluations of foot structure and pastern angles. While no major structural issues were found, 13 bulls had suboptimal claw scores or pastern angles. McGregor cautions against breeding with bulls showing poor structure, as it may pass undesirable traits to offspring.

MU Extension’s BSE Days are a collaborative effort with veterinarians and pharmaceutical companies to educate producers and support informed herd decisions.

Veterinarians in southwest Missouri interested in participating can contact their local MU Extension livestock field specialist.

Photo Credit: gettyimages-steveoehlenschlager