Can I Use a Carrier Bull?

February 2010

This spring there will be some bulls sold in sales or private treaty that are carriers for genetic defects.

The question commercial producers have to answer is, "Can I safely use a carrier bull?". This requires knowledge of your cowherd. If there is a risk that your cows are also carriers, then you should avoid mating them to a bull that is a carrier of the same defect as the cows. However, if you are confident your cows are clean (i.e. non-carriers) then you should choose the bull, based on EPDs and Indexes, that best fit your breeding objectives regardless of his genetic defect status.

In the simple scenario of breeding an Angus bull to another breed of cows (i.e. Hereford) then a carrier bull can be used with confidence. Make sure in this scenario that you do not breed any replacement heifers from this mating to another carrier bull.

The only time genetic defects are of concern is when there is the potential to mate a carrier bull to carrier cows. In this case, we would expect on average that 25% of the claves would have the defect. Mating a carrier bull to clean cows will result in zero defect calves.

The take home message is to have knowledge about your cow herd and do not eliminate the best bull from your short list because he is a carrier if you can safely use him.

Dr. Matthew Spangler, Assistant Professor of Animal Science
Animal Science, University of Nebraska–Lincoln, Lincoln NE, NE