• Tori Lewis

Does fertility testing bulls make sense?


Yearly bulls being tested before a bull sale.

Lets face it, handling bulls is not always a fun way to spend the day. You never really know if they are going to gather well or start fighting amongst themselves. Are they going to tear up the corals or damage equipment? Is all of that headache worth it?


For most of us, a day of super hard work needs to have some economic value, so looking at the cost benefit of going through a fertility test may help establish that value.


A general rule of thumb is that one bull needs to successfully cover 25 cows. Not every operation is able to have that ratio, due to rugged country or if cows are dispersed over a large area, sometimes that number is lower. For our evaluation, though, lets figure that he is responsible for 25 calves in the spring. If each calf sells at a round number of $1000, he is responsible for producing $25,000 for the year. If he, however, is not able to do is job that number decreases proportionally and the rancher sustains a significant economic loss. In addition to the cost sustained due to a decreased calf crop, it costs anywhere from $700-$900 to feed that bull for the year, and $600-$800 to feed every one of the cows he did not get bred. In a cattle market where the difference between running in the black and running in the red is a pretty narrow line, these numbers are significant.

There are many reasons that a bull could not be able to do his job. He may not be healthy enough himself to breed cows. Maybe he has a bad foot and can’t travel, or properly mount a cow. Perhaps is eyesight has been damaged and he can’t see to follow cows. Of course, the other big reason would be if he did not have the ability to properly produce and deliver sperm to the cow. It would make sense then that if we were to test a bull for their fertility, we would look at all of these things, so we do.


As the bull approaches the chute, the veterinarian and their technical staff are looking for how the bull moves, what is his body condition score, is he able to see where he is going, and if there are any scars on his eyes, will they likely inhibit his ability to do his job? While the vet is collecting a semen sample for analysis, they are looking at his feet making sure there are no wounds or toes starting to cross.


Dr. Panning evaluating a semen sample under the microscope.

The semen sample is evaluated according to industry standards and a passing, failing, or deferred status is given. If the bull has failed his test, and about 10% do, he should be culled and a replacement found. He will not be successful getting the job done. A deferred status can only be given to bulls under two years old, and they are allowed to be retested at a later time to establish if they were just not yet mature enough, or if they are truly a bull that will not perform successfully.

More information can be gathered on bulls that pass, than simply knowing they are good for the year. If, for example you have 2 bulls that are 4 years old, and you would really like to plan for one of them to breed as a 5 year old in order to spread the cost of replacement bulls out, you can look at the quality of the semen samples and it is likely that one is better than the other. In fact, planning for bull replacement should be an active yearly process based on their fertility test. Injuries to bulls and their reproductive system can happen during the breeding season, and finding injuries that where not present the year before is a fairly common reason bulls will fail their fertility test. Testing bulls yearly before they are turned out with the cows is the only way to be sure that the bull is ready at the time of breeding season.




In some areas bulls should be tested for Tichomoniasis. We work with our producers to establish which bulls need to be tested to keep a herd safe from that infectious disease and the devastating economic effects that result from it.




Since one bull has the responsibility to successfully produce 25 calves the cost of fertility testing and making sure those 25 cows are covered is a small cost in comparison to the loss sustained by relying on a bad bull.

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