Bulls – Breeding Soundness Exam (Semen Testing)

June 11, 2020

Evaluating bulls prior to the breeding season can prevent significant economic loss.  This is especially true in small herds (most beef herds in Ontario) for a couple of reasons:

1. Each open cow represents a proportionately larger economic loss

2. There are fewer bulls (maybe only 1) running with the cows, leaving less room for error

It is much less costly and frustrating to identify a dud bull before the breeding season, versus at preg-check or calving time.  A breeding soundness exam includes the following:

Physical & Ultrasound Exam Evaluates the physical characteristics of a bull necessary for mobility in the pasture, structural soundness, and overall internal and external reproductive tract development.
Scrotal Circumference Evaluates testicular size and health, as well as estimating the bull’s sperm-producing capacity (minimum measurements based on age, breed)
Sperm Motility Ensures that the bull is producing sufficient live motile sperm
Sperm Morphology Ensures that the bull is producing sperm that are properly shaped and capable of fertilization

A bull is then categorized as fertile, sub-fertile, or infertile (sterile).  Infertile bulls are often easily identified and culled.  Sub-fertile bulls are sneaky in how they drain your bottom line: even though they may eventually get cows pregnant, they will take much longer than fertile bulls. In other words: fewer calves + more later-born calves (lighter at weaning) = fewer pounds of beef raised per exposed cow.

If you have any questions on this or other topics, please do not hesitate to contact one of our Veterinarians.

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