Bull Testing

This is the time of year where we get our bulls ready for the upcoming breeding season. The breeding season won’t start for awhile but if we wait too long we may not be able to get a vet out to bull test. We need bulls tested early in case we need to replace some. This gives us plenty of time to pick out a quality bull.


So why bull test? Simple. If we don’t bull test, we run the risk of having a dominant bull that isn’t preforming yet keeping bulls that are from breeding. A situation like that can lead to a lot of open cows at preg check time, and a very large expense in replacing those cows. Moreover, it gives us the opportunity to look over bull’s physical condition. Sometimes a younger bull will develop traits we would rather cull.

So yesterday we had an appointment for the vet to come out and test our bulls. The appointment was at 1:00, which is unusual because usually the vet likes to come for dinner too (cut him slack, it is still calving season). After feeding we saddled up to go round up the bulls. Bulls don’t move like cows, it is more like herding cats. They don’t really move in a herd. They bawl and fight each other. They randomly take off running in the wrong direction and if they get tired they will turn and challenge your horse (my horse is scared of bulls, so when this happens my game is over).

My mother in law saddled up to come but feeding took longer than expected and we all decided if we wanted homemade cinnamon rolls and fried chicken for dinner, we could get along without her. For the most part the bulls moved well (as well as bulls can move). We didn’t have to move them very far to the corrals. We put them each in separate pens while waiting for the vet so they wouldn’t fight each other (bulls are VERY hard on fences and corrals, they once bent a metal gate in so far there was a 2 foot gap when you went to close it).

The vet didn’t show up till 4:00 pm due to some emergency calving calls that came into the vet clinic and the other vets weren’t on duty. When he showed up we were ready to test.

This is my second time participating in bull testing, so I’m pretty green. A note to those just starting in the bull testing arena: When the vet asks you to take the job titled “rear admiral” be wary.

Bulls are tested using a probe that is inserted into the bull the only place things can be inserted into a bull….the rear. The vet controls the probe to produce a sample from the bull of which he looks at under a microscope. My job was to insert the probe, then remove the probe, and clean it for the next bull. It is not the most glamorous job to have, but getting a responsibility is always exciting! I was glad to get the “crappy” job.

Our vet has his probes named, the one we used was called Keystone. He also had one called “The Stimulus Package”, “Obamacare”, “NSA”, and “Gary” (Gary is another vet). Our vets are so clever.

One of our bulls tested poorly and we’ll have to sell him. There was another who had bad conformation of the hooves and we’ll sell him too. We don’t like selling bulls because replacing them isn’t cheap.

There were a couple bulls who had to be tested twice. The vet told me that because the bulls have not been actively breeding, the semen can get “stale” for lack of a better term. The second testings produced better samples. A couple of our bulls performance actually had improved from last year.

So what do we test for? People who sell breeding bulls have all kinds of EPDs (expected prodeny differences). We don’t raise breeding bulls so our test are not near as extensive. When the vet looks at the sample from the bull he looks for a few things:

  • Concentration- essentially a sperm count
  • Motility- how much the sperm moves (better movement increases the chances of fertilization)
  • % Normal- how many of the sperm cells are normal (i.e. not dead or deformed)

The vet will then measure the scrotal circumference. This measurement is found to be directly linked to fertility. The larger the measurement, the more fertile the bull.


All of these factors can change from year to year in a bull which is why we test yearly. One factor of breeding that cannot be assessed in a bull test is a bull’s drive and ability to mate. This is why it is important to occasionally watch your bulls to assure they are breeding.

I found a couple really great articles from extensions that explain predicting bull fertility:
University of Missouri Extension, Determining Reproductive Fertility in Herd Bulls
Virginia Cooperative Extension, Predicting Bull Fertility

I did not get pictures of bull testing as the job “rear admiral” leaves little time for photography.



3 thoughts on “Bull Testing

    1. glattheranch Post author

      Cut me some slack woman! I have one coming we pulled another calf! I haven’t really seen an actual blog post describing the joys of outback fencing and dirt bike “tyre” fixing in a fortnight x10. #jilleroofail ! Ps. If you a
      Start school in Aug that leaves you time to come crash at the ranch and then it is wild burro buckout round 2!!!!!


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