Schedule Breeding Soundness
Exams Soon
Prepare for breeding season by testing bulls for breeding soundness.
Although the spring calving season may still be ongoing, the next breeding season is only a few weeks away. Now is the time to schedule old and new bulls for their prebreeding soundness examinations.
For the breeding soundness evaluation (sometimes referred to as a BSE) to be successful, bulls should be evaluated 30 to 60 days before the start of breeding. It is important to allow sufficient time to replace questionable bulls. Bulls could also be evaluated at the end of breeding to determine if their fertility decreased. A breeding soundness exam is administered by a veterinarian and includes a physical examination (feet, legs, eyes, teeth, flesh cover, scrotal size and shape), an internal and external examination of the reproductive tract, and semen evaluation for sperm-cell motility and normality.
The physical examination studies overall appearance. Flesh cover is one factor to evaluate. Body condition can be affected by length of the breeding season, grazing and supplemental feeding conditions, number of cows the bull is expected to service and distance required to travel during breeding. Ideally, bulls should have enough fat cover at the start of breeding so their ribs appear smooth across their sides. A body condition score 6 (where 1 = emaciated and 9 = very obese, more information can be found at www.cowbcs.info) is the target body condition prior to the breeding season.
Sound feet and legs are very important. If they are unsound, this can result in the inability to travel and mount for mating. The general health of the bull is critical because sick, aged and injured bulls are less likely to mate and usually have lower semen quality.
The external examination of the reproductive tract includes evaluation of the testes, spermatic cords and epididymis. Scrotal circumference is an important measure since it is directly related to the total mass of sperm-producing tissue, sperm cell normality and the onset of puberty in the bull. Bulls with large circumference will produce more sperm with higher normality and also reach sexual maturity sooner.
Examination of the external underline before and during semen collection will detect any inflammation, foreskin adhesions, warts, abscesses and penile deviations. The internal examination is conducted to detect any abnormalities in the internal reproductive organs. Also, be certain to ask your veterinarian about the need to test the bulls for the reproductive disease trichomoniasis. Learn more about this disease by downloading and reading the Oklahoma State University (OSU) fact sheet VTMD-9134 Bovine Trichomoniasis.
The semen evaluation is done by examining a sample of the semen under a microscope. The veterinarian will estimate the percentage of sperm cells that are moving in a forward direction. This estimate is called “motility.” In addition, the sperm cells will be individually examined for proper shape or “morphology.” Less than 30% of the cells should be found to have an abnormal shape.
Any bull meeting all minimum standards for the physical exam, scrotal size and semen quality will be classed as a “satisfactory” potential breeder. Many bulls that fail any minimum standard will be given a rating of “classification deferred.” This rating indicates that the bull will need another test to confirm status. Mature bulls (that were listed as classification deferred) should be retested after four to six weeks. Mature bulls will be classified as unsatisfactory potential breeders if they fail subsequent tests.
Young bulls that are just reaching puberty may be rated as “classification deferred,” and then later meet all of the minimum standards. Therefore, caution should be exercised when making culling decisions based on just one breeding soundness exam.
Many producers work hard to manage their cows for high fertility. They may assume that the bulls will do their expected duties. However, it’s important to pay close attention to bulls to establish successful breeding.
Editor’s Note: Glenn Selk is an Oklahoma State University emeritus extension animal scientist. Reprinted with permission from the March 9 Cow-Calf Corner newsletter published by Oklahoma Cooperative Extension.