The goal of a breeding soundness exam is to determine the physical ability of a bull to efficiently breed a cow and the health of his sperm cells. A complete breeding soundness exam evaluates three categories: 1) physical soundness, including feet, hip, and leg structure, body condition, vision, penis, accessory sex organs, and the ability to ejaculate, 2) scrotal circumference, and 3) semen characteristics - sperm cell motility (movement) and morphology (physical shape). Based on the results in each of these three categories, a veterinarian classifies the bull as satisfactory (pass), unsatisfactory (fail), or deferred (retest). A satisfactory breeder meets the minimum requirements in all categories and is free of physical problems. Bulls that do not meet the minimum requirements in at least one of those categories are unsatisfactory or deferred for another evaluation at least 30 days later. Unsatisfactory breeders likely will not improve with time, but deferred bulls may benefit from treatment or additional time and pass a breeding soundness exam in the future, such as young bulls who need more time to reach full sexual maturity. Scrotal circumference: This measurement estimates the bull’s sperm production capacity and testicular health. The scrotal circumference is measured by applying a flexible tape around the largest circumference of the scrotum. The minimum threshold for scrotal circumference depends on the bull’s age. The semen is examined under a microscope as a group and individually. As a group, it is evaluated for what percentage of the semen are moving in a semi-straight pattern across the slide. This helps determine the odds of the semen reaching the egg for fertilization. The semen are then killed with a special stain to evaluate the shape of each individual sperm cell. Abnormalities like double heads or twisted tails help determine the overall health of the semen and likelihood of a successful breeding and healthy calf being produced. It is recommended that all bulls have a breeding soundness exam each breeding season whether they are new or a resident herd sire. Because sperm production is a continuous process and bull fertility can change over time, the BSE should be performed close to the start of the breeding season. Ideal timing for the exam is 30 to 60 days prior to turnout. On average, 20% of bulls will be unsatisfactory at the time of the BSE. BSE BASED ON THE NATIONAL SOCIETY FOR THERIOGENOLOGY STANDARD
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