Dr. Rosslyn Biggs, on Bull Breeding Soundness EvaluationsWed, 21 Apr 2021 09:28:04 CDT
Dr. Rosslyn Biggs, OSU College of Veterinary Medicine Extension Beef Veterinarian writes on bull breeding soundness.
When selecting bulls, producers should not overlook a breeding soundness evaluation (BSE) conducted by a veterinarian before the breeding season.
Standards for breeding soundness evaluations have been established by the Society for Theriogenology (SFT), a group of veterinarians dedicated to animal reproduction. Although many may use the term “semen testing,” a breeding soundness evaluation is much more. A complete breeding soundness evaluation involves a physical examination, reproductive tract examination, and semen evaluation.
The physical examination of the bull begins with a focus on structural soundness and checking for injuries. The eyes and oral cavity are evaluated. Assessing body condition is also key. 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.
The second component of the BSE is focused on the reproductive tract. Scrotal circumference measurements must meet established minimum requirements. 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, prepuce and scrotum for physical defects such as congenital abnormalities, warts or injury.
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%. A special stain is later added to evaluate the structure of sperm cells. Greater than 70% normal sperm must be present. The semen sample is also evaluated for other cells indicating infection.
Under the SFT classification bulls are considered:
1. Satisfactory potential breeder
2. Unsatisfactory potential breeder
3. Classification deferred
If classification is deferred, then a producer should work with their veterinarian to reevaluate the bull. It is very important to understand that a BSE is an evaluation on the day the test was performed only, and there is no lifelong guarantee of bull fertility. Bulls should be tested 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 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.
To view Dr. Johnson and Dr. Parker Henley talk about breeding soundness exams before turning bulls out on Sunup TV Cow-Calf Corner from April 17, 202
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