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UNL Extension
A good bull is the cornerstone of any cow-calf operation. Cows influence the genetic makeup of only one calf each year, but a bull has the opportunity to impact 20 to 50 calves depending on the breeding season. Because of that, making sure bulls are able to locate and breed cows successfully is vital. One of the best ways to evaluate that potential is with a breeding soundness exam, or BSE.
At a minimum, young bulls entering their first breeding season should have a BSE, along with older bulls that have experienced a health problem, injury, or possible scrotal damage from extreme cold during the winter. More broadly, having a veterinarian perform a breeding soundness exam on all bulls 4 to 6 weeks before the breeding season is a good idea. Given some of the weather challenges this past winter, producers may want to schedule exams a little earlier than normal so bulls that are below acceptable standards can be retested, and replacements can still be found before turnout if needed.
A breeding soundness exam includes a physical exam, an internal and external evaluation of the reproductive tract, and a semen evaluation.
The physical exam looks at overall bull health. Bulls exert a great deal of energy during the breeding season as they travel and service cows, and they often lose body condition over that time. Because of this, they should enter the breeding season in fairly good condition, with a body condition score of 6 as a good target. Sound feet and legs are also important, since problems in either area can limit a bull’s ability to travel, mount, and breed cows successfully. General wellness matters too, as injured, sick, or older bulls may be less likely to settle cows and may also have lower-quality semen.
The reproductive tract evaluation is used to make sure there are no obstructions, injuries, or other abnormalities. The testes, spermatic cords, epididymis, and external underline are all examined. Scrotal circumference is also measured and recorded because it is related to the amount of sperm-producing tissue and to sperm cell normality. An internal examination is conducted as well to identify any abnormalities in the internal reproductive organs.
The final step is a semen evaluation, where a sample is examined under a microscope. The veterinarian estimates the percentage of sperm cells that are moving forward, known as motility. Sperm cells are also examined for proper shape, referred to as morphology. Less than 30 percent of the cells should be abnormal.
Any bull meeting minimum standards for the physical exam, scrotal size, and semen quality is classified as a satisfactory potential breeder. Bulls that do not meet a minimum standard may receive a classification of deferred, meaning another test is needed to confirm status. Mature bulls should generally be retested after six weeks. Young bulls that are just reaching puberty may be classified as deferred at first, then later meet minimum standards as they continue to mature. Bulls that fail later tests may ultimately be classified as unsatisfactory potential breeders.
Cows often get much of the attention when herd fertility is discussed, but a complete fertility program also requires attention to bull health. A breeding soundness exam is a valuable tool to help reduce risk and improve confidence going into the breeding season.
—Ben Beckman is a beef systems Extension Educator serving northeast Nebraska. He is based out of the Cedar County Extension office in Hartington. You can reach him by phone: (402) 254-6821 or email: [email protected] mailto:[email protected]
