Veterinarian Dr. Roy Lewis believes that breeding soundness exams (BSEs) are an essential part of beef herd management. Although BSE is an expense, it can save money.
For those considering BSE for the first time, Lewis said it’s easy to justify by adhering to the well-known maxim “the bull is half the herd.”
“By semen-evaluating bulls, we can help steer the direction of herd fertility,” he said. “The equivalent is looking at all the cows, but we’re doing the BSE as a preventative, ahead of the breeding season. When we find open cows, it’s usually too late. We can avoid issues and up the bull-to-cow ratio and find out which ones are the true breeders.”
BSEs can save feed costs while there’s still an opportunity to replace a bull, and purebred breeders have learned it’s a win-win situation. “They realize that getting problem bulls out is good because they aren’t going to have to sell them and deal with the consequences,” said Lewis. “It’s good for purchasing bulls knowing the fertility aspect has been checked and is good.”
Lewis reviewed the history of semen evaluation: “AI has been done since the 1950s, and the 1970s brought better semen evaluators. Veterinarians were taught about semen evaluation in vet school and demand was starting to come from commercial breeders who purchased purebred bulls and wanted semen-tested bulls.”
Purebred breeders realized it was worth doing BSEs on a prospective sale bulls to provide added confidence for bull buyers.
In some purebred sales, bulls are too young for semen testing. For young bulls, scrotal measurements are recorded and a physical exam will check for sound, healthy reproductive glands. The purebred breeder will then semen test prior to delivery.
For conducting BSEs, Lewis prefers hydraulic chutes, but said any good, sound chute system will work. While warm weather is ideal, BSEs can be done in cold weather with heat blown under the chute and the microscope is kept in a heated vehicle.
On some farms, good maternity pens can be reconfigured to test young bulls. Lewis said veterinarians are experienced improvisors and can usually figure out how to safely manage an exam with available facilities.
Part of the exam involves measuring the scrotum and examining the reproductive organs. On young bulls, the vet will look for penis problems, sheath warts or scars from healed cuts.
“These aren’t common but if we find them, we can correct the problem right away and the bull has a good chance to go on to be a good breeding bull,” said Lewis.
If the examining vet discovers warts, sometimes surgery is worthwhile, but it’s important to make sure the bull can successfully breed with a good semen count after surgery.
Libido, or the ability to breed, is mostly up to the owner to evaluate. It’s a matter of the owner watching new bulls, especially yearlings, as they breed the first several females. It doesn’t take long to figure out which bulls are awkward breeders, and whether they improve over time.
For semen evaluation, all registered breeds have a breed minimum, and Lewis has found that breed minimums are reliable. “I’ve tried a few bulls that were just under breed minimum and without a doubt they would fail to where we couldn’t get a semen sample,” he said. “It’s different for different breeds and ages, but it’s been researched and well-substantiated over the years.”
Historically, scrotal circumference measurements have been taken using everything from tape measures to seamstress tapes, but new tapes are vastly improved. A scrotal circumference measurement above 38 to 39 cm doesn’t mean extra semen production or fertility. “If they’re too big we see problems,” Lewis said. “They break down or get caught on things.”
Scrotal circumference is often adjusted to one year of age. “They change a lot,” said Lewis. “At 10 to 15 months of age, they can grow several centimeters per month, which can make a big difference in comparing a 13-month to a 15-month bull.”
Lewis prefers to wait until a bull is 12 months to conduct a full BSE. Some bulls fail the BSE at that age but often improve with age.
Part of the BSE includes a good physical soundness exam, including observation of feet and legs as the bull walks. A bull may pass the semen evaluation but may not have ideal conformation, and this should be noted for buyer transparency. Physical characteristics noted include general health, eyes, feet and legs, scrotum, testes, epididymides, accessory sex glands and inguinal ring.
Lewis said that while it’s important to note bull behavior, it’s rare to find a bull with a poor temperament because breeders have selected for docility.
During BSEs, bulls should be treated as quietly as possible and without stress so they can provide a good sample. When a hydraulic chute is available, bulls can be fairly loose in the chute so they will stand better.
“Don’t catch their heads unless necessary,” Lewis said. “Take it nice and slow … Give the bull every chance to give a good sample. Bring bulls in as a group and return them as a group to avoid fighting.”
Because bulls are somewhat more difficult to handle in general, having them in the chute for BSEs is a good opportunity to complete other management steps such as vaccinations or parasite treatments.
A BSE should be conducted as close to breeding season as possible. Farmers with commercial herds try to do BSEs close to turnout, but some opt for an earlier exam to determine whether the bull will pass or fail. This allows ample time to get another bull and perform the BSE.
Commercial producers who breed in spring but have already purchased a bull several months earlier may choose to retest just prior to turnout.
Some herds that breed during different seasons share bulls if disease status is known. This allows more use of a high-quality bull. Each producer should semen test prior to breeding season.
Since the BSE is a critical component of a productive herd, Lewis urged producers to keep accurate records on the results of the BSEs and be prepared to refer to previous BSEs to compare results and determine whether a bull should remain in the herd.
by Sally Colby
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