Bull Breeding Soundness Exams
Wednesday, April 22, 2026
As spring approaches, the breeding season grows near and the genetics of future calf crops will be top of mind for producers. One way to maintain and improve genetics is to require a thorough evaluation of all new as well as existing bulls.
Several factors go into addressing bull evaluation. These include whether a bull is appropriate for a set of cows, such as age, pedigree, phenotype, EPDs, and other parameters. The one selection criteria that cannot be overlooked is a breeding soundness evaluation (BSE) conducted by a veterinarian.
Standards for breeding soundness evaluations have been established by the Society for Theriogenology (SFT) which is a group of veterinarians dedicated to animal reproduction. Although many may use the term “semen testing,” a breeding soundness evaluation goes well beyond just looking at semen under a microscope.
This is because semen itself may be of acceptable quality, but the bull may not be physically able to breed. A complete breeding soundness evaluation as outlined by the SFT involves a physical examination, reproductive tract examination, and semen evaluation.
The physical examination of the bull begins with a primary focus on structural soundness and checking for injuries to the feet and legs. The eyes and oral cavity, especially teeth, are evaluated. Assessing body condition is another key component. Bulls that are too thin and those that are too fat are problematic. Thin bulls may not be able to maintain themselves during a physically demanding breeding season. Bulls that are fat may have difficulty adjusting to living in range conditions and are also predisposed to joint injuries. Bulls in a body condition of 5 to 6 are generally ideal.
The second component of the BSE is focused on the reproductive tract anatomy and health. Scrotal circumference measurements must meet established minimum requirements correlated with age of the bull. Palpation of the testicles and spermatic cords, along with rectal palpation of internal organs is required. Electroejaculation is the most common method used to obtain a sample for semen evaluation. It also allows examination of the penis and prepuce for physical defects such as congenital abnormalities and warts.
Semen evaluation is a microscopic examination of motility (movement) and morphology (structure) of sperm cells. These indicate the quality of the semen. Cells should move rapidly and in a linear fashion, and individual progressive motility must be at least 30%. Environmental factors, such as cold external temperatures, can impact semen so motility evaluation should be conducted quickly to avoid environmental influence. Once motility is assessed, a special stain is added to evaluate the structure of sperm cells on the microscope slide. Greater than 70% normal sperm must be present. The semen sample is also evaluated for other cells that may indicate infection.
Under the SFT classification bulls are considered:
- Satisfactory potential breeder
- Unsatisfactory potential breeder
- Classification deferred
If classification is deferred, then a producer should work with their veterinarian to set up a time to reevaluate the bull. It is very important to understand that a BSE is an evaluation on the day the test was performed only. Remember, whatever was collected today, the testicle started producing the sperm 60 days ago. With this cold weather in January and February and the outside temperature being below freezing for extended period of time, the factory/testicle is lifted close to the body, and is detrimental to make good quality sperm from the testicle. Frost bite on the scrotal skin and penis may be a problem with this cold weather. It is important bulls undergo a breeding soundness evaluation before the breeding season, to make sure the bull is physically sound and producing quality semen, and there has not been any longterm effects on the testicles.
There is no lifelong guarantee of bull fertility due to the variety of factors that may lead to reproductive failure. Producers should work with their veterinarian to test bulls at least annually. For new purchases, buyers should request documentation of the BSE.
Producers may also discuss other diagnostic testing, including sampling for infectious diseases, such as Trichomoniasis, with their veterinarian. Continued evaluation of a bull to evaluate libido and maintenance of body condition through visual observation should also occur during the breeding season. This, combined with annual evaluation of bulls, will get next year’s calf crop off to a great start.
Written by: Dr Lionel J. Dawson DVM, DACT