Check Bull Performance With a Complete BSE

Bull Performance Insurance

Rather than take chances with an infertile bull, veterinarian Billy Blair Jr. and cattleman Austin Taylor both believe in Breeding Soundness Exams. (Becky Mills)

You probably don't know Joe Dalton, but he lies awake at night worrying about your herd. Specifically, the University of Idaho (UI) animal scientist frets because you might be one of many producers who doesn't do a complete Breeding Soundness Exam (BSE) on your bulls every year.

More than likely, you did your homework at bull-buying time. An average of 67% of you make sure you buy a bull with a passing BSE. But, then, according to a recent National Animal Health Monitoring System (NAHMS) survey, you slack off. Only an average of 31% of producers test bulls they've had in their battery for at least two breeding seasons.

Adel, Georgia, cattleman Austin Taylor is one of the 31%. He has BSEs done on the 18 to 20 bulls in his bull battery every year. "It's an insurance policy. I want to make sure they can breed a cow. I've had them go bad and not know it," he says.

HEAT-STRESS DANGERS

Sure, you can spot the obvious, such as your best bull hobbling around on three legs. There are more subtle catastrophes, though, including heat stress. Normal body temperature for a bull is around 101.5°F, but to keep the sperm factory going, the scrotum needs to stay around 94 to 96°F. Let a bull overheat, maybe on the way to the catch pen or in a trailer, and he could be out of the healthy sperm business for the length of your breeding season.

"Spermatogenesis is a 60-day process," says Kalyn Waters, Holmes County, Florida, county Extension director and cattle owner. "However, heat stress can impair spermatogenesis for up to 100 days."

Waters says the cremaster muscle in the scrotum helps a bull with thermoregulation by pulling his testicles closer to his body when it is cold or lowering them as temperatures rise. "When it is hot, and you see those testicles swinging, do not let a bull get out of a walk," she warns.

Heat stress can also happen due to a fever or if the bull is overconditioned. "The fat in the scrotum makes it harder for him to thermoregulate," Waters notes.

To be on the safe side, get the bull tested at least 60 days before turning him in with cows. The reason? It takes 60 days for him to produce sperm from start to finish, but if he fails, you have time to replace him.

And, fail he might. In a 10-year study out of Michigan with almost 3,000 beef bulls, 82% of bulls were satisfactory, 15% were deferred and 3% were unsatisfactory after complete BSEs. In a second study, 1,200 BSEs on beef and dairy bulls were done, and 37% were unsatisfactory. "That keeps me awake at night," Dalton says. "That's a huge problem."

Make no mistake, the studies reflect a complete BSE, not just a semen test. There was also a study done with 200 Holstein bulls, 12 to 15 months of age. "They were plenty old at 12 to 15 months of age, but 36% were unsatisfactory," Dalton says. "Here's the kicker: 57% of those bulls failed because of the physical exam alone. That's why a semen test, taking a sample, looking at motility, looking at morphology and saying, 'Yep, all is good,' is not sufficient."

STEPS TO TAKE

For a complete BSE, start with the bull's eyes. He needs two of them, healthy ones. "The primary cue to a male of a female in heat is eyesight," he explains.

Next in line are his feet and legs. Jennings, Florida, veterinarian Billy Blair Jr. says, "I watch the way he walks in the chute. Evaluate his feet, look for corns between the toes and cracks in his toes."

Blair does an internal exam by rectal palpation and checks the prostate and both ampullae. Then, he measures scrotal circumference, which should be a minimum of 32 centimeters (cm) for a 12-month-old bull and 34 cm for a 14-month or older bull. This is a big deal. Scrotal circumference is an indirect estimate of sperm production potential. Plus, researchers have found time and again that scrotal circumference is negatively correlated with the age his daughters reach puberty. If he has a smaller scrotal circumference, his daughters tend to reach puberty later -- not a trait you want to breed into your cow herd.

He also palpates the testes. "Check the uniformity and softness of the testicles," Blair continues. "They shouldn't be mushy but should be firm. If they are too soft or hard, that'll show up in motility and morphology problems.

"Extend and look at the penis," he adds. "A persistent frenulum can attach from the sheath to the tip of the penis and pull the penis back." Blair says this is a fairly simple fix. However, with older bulls, you may see injuries to the penis or sheath with scar tissue so the penis can't extend.

Next is the semen evaluation with a sample normally collected by electroejaculation. Blair puts a small amount of semen on a slide, stains it and examines it through a microscope. He's looking for at least 30% progressive motility, but 70% or higher is preferable. That means the little swimmers can travel in a fairly straight line toward the target. Morphology should be 70% normal or higher, with a minimal number of broken tails and misshapen heads.

Still, when you turn your bull out with your cows or heifers, make sure he is actually breeding them. Libido is hard to measure, so your eyes on the pasture is the best way to make sure he's doing his job.

Yes, getting bulls up to do BSEs is as aggravating as it gets, especially if you must trailer them to the pen. You might not even have a chute wide enough for a mature bull. Plus, it is an added expense.

In Dalton's part of the world, BSEs typically cost $50 to $65 a bull, depending on how far the vet has to travel to get to a ranch. However, he says it's money and time well spent. "I like insurance. The benefit-to-cost ratio is $20 for each $1 invested."

He'll also sleep better.

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