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Breeding soundness exams are crucial to setting bulls up for success

by Wyoming Livestock Roundup

“Bulls make up one-half of the genetics of a herd, and conducting a breeding soundness exam (BSE) can really steer an operation in the right direction as far as reproduction and fertility go,” states Merck Animal Health Veterinarian Dr. Roy Lewis during the second webinar of the Beef Cattle Research Council’s (BCRC) Record Keeping for Production Management informational series. 

During the webinar, Lewis discusses the value of conducting BSEs. 

“I know I’m preaching to the converted, but I hope I can give producers – commercial and purebred alike – some tips and tricks to help conduct BSEs on their operations,” he adds. 

Components of a BSE

Lewis explains during a BSE, veterinarians measure and evaluate scrotal circumference, semen quality, semen morphology, libido and other physical characteristics important for breeding, such as soundness of feet and legs.

“All breeds have a minimum for scrotal size based on breed characteristics and age, which I believe are right on the money. These numbers have been extensively researched and substantiated, and I firmly believe in them,” he says. 

Although scrotal circumference is correlated to sperm motility, percentage of normal sperm and the age at which a bull’s daughters reach puberty, Lewis notes problems arise when testicles are too big. 

“Scrotums measuring over 50 centimeters, don’t last. They break down or get caught on things. There are a lot of problems that can arise,” he says. 

For libido evaluation, Lewis says it really comes down to the opinion of the producer. Since there isn’t an exact measure for this component of a BSE, it depends on the producer’s confidence in each bull on their ability and desire to breed. 

“A very important component of a BSE is to serve as a good physical soundness exam,” Lewis continues. “It’s important bulls can travel, so we want to watch them walk. While we are collecting semen, we should take a good look at the bull’s feet and legs.” 

Veterinarians will also be on the lookout for physical defects of reproductive organs, such as persistent frenulums, warts, cuts, hair rings, etc. 

“These issues are not very common,” he says. “When we find them there is a good chance we can correct the problem right away, and the bull will still be good for breeding.” 

“Persistent frenulums are genetic, which isn’t much of an issue for commercial breeders because they can still breed fine,” he continues. “However, I would advise purebred breeders from buying bulls with this defect.”

As far as semen testing goes, Lewis says both quality and morphology are important to evaluate. 

He explains this includes looking for sperm malformations, such as head defects or coiled tails, which makes it impossible for sperm to swim. 

Equipment and facilities

According to Lewis, the equipment and facilities used to conduct a BSE are essential to the process. 

While working facilities don’t have to be anything fancy, he notes it is imperative to handle bulls calmly, quietly and slowly. 

In order to keep the process as stress-free as possible, he says he likes to leave bulls loose in the chute, without catching their heads. 

“I’ve found they stand better this way,” he states. “I don’t like to catch their heads unless they are really high strung. It’s important to work them slow and steady.” 

Lewis also notes it’s important to have good, reliable equipment when conducting a BSE. 

“Like any equipment, some brands are better than others, and every new model is a little bit better than the last,” he says. 

Other considerations

Before concluding his presentation, Lewis offers a few considerations for producers to keep in mind while conducting a BSE. 

First, he encourages producers to take care of other management practices while bulls are in the chute. 

“In general, bulls are a little bit harder to handle. So, if there is anything else a producer needs to do – vaccinate, treat parasites, retag, etc. – it is a great opportunity to do so,” he says. 

Additionally, Lewis notes some bulls are harder to collect than others for a number of different reasons. 

For bulls that are refractory to the electroejaculation probe, he suggests using a simple massaging technique, and for bulls that are hard to stimulate, he recommends letting them breed an actual cow, then drawing out the semen from the vaginal canal. 

“BSEs are really a win-win,” Lewis concludes. “Producers are able to identify and eliminate problem bulls, and they don’t have to deal with the consequences of selling these problem bulls. It is also beneficial for people who purchase bulls because they know bulls are adequate as far as fertility goes, and they can have confidence in these bulls moving forward.” 

Hannah Bugas is the managing editor of the Wyoming Livestock Roundup. Send comments on this article to

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