A good manager keeps an eye on his bulls during the breeding season to make sure that
they are getting the cows inseminated. Occasionally a bull that has passed a Breeding
Soundness Exam may have difficulty serving cows in heat, especially after heavy
service. Breeding Soundness Exams cannot evaluate bull libido. Such problems can best
be detected by observing bulls while they work. “Libido” or sex drive refers to the desire
to mate and is thought to be a highly heritable trait in cattle. Remember that semen
quality and scrotal circumference are not related to libido. Therefore, a bull that passes a
Breeding Soundness Evaluation may have poor libido, or a bull with good libido may fail
a Breeding Soundness Evaluation.

Therefore producers should (if at all possible) watch bulls breed cows during the first part
of each breeding season. If problems are apparent, the bull can be replaced while
salvaging the remainder of the breeding season and next year’s calf crop. Likewise a
small proportion of bulls can wear out from heavy service during the breeding season and
lose interest. These, too, will need to be replaced. The greater the number of cows
allotted to each bull in the breeding pasture the more critical it is that every bull be ready
to work every day of the breeding season.

Injuries to bulls during the breeding season are relatively common. When a bull becomes
lame or incapable of breeding, because of an injury to his reproductive tract, he needs to
be removed from the breeding pasture and replaced with another bull.