There are advantages to a multi-bull breeding program. First, in my mind is the fact that any bull can “go bad” at any time. It may not be obvious when it happens, and he can still breed cows. Also, if multiple cows come into heat at the same time, multiple bulls should be more efficient at tending and setting them up. There is also less need for fencing and working facilities with the multi-father approach. Larger pastures can be used, or you can alternate between multiple pastures depending on forage availability. The multi-bull program is one of my favorite management practices.
Like all good things, there are also some possible downsides to consider. At the top of the list, injuries to bulls, and even cows, increase when there are multiple bulls in the herd. You also don’t know the sire of a calf without a DNA test. And if the “boss” bull is infertile, he can push away the fertile bulls, preventing the cows from getting pregnant.
I found a study that looked at multi-sire breeding programs in multiple large herds. These researchers found that, on average, bulls produced 15–20 calves per breeding season; however, some bulls have sired more than 50 calves. And 7.3% of the bulls in the program produced no calves. In at least half of the breeding seasons, at least one bull was retired due to injury or poor condition.
All of this tells me that very prolific bulls will have a disproportionate impact on the genetic tendencies of the herd. Are these bulls genetically superior bulls? Do we want these prolific bulls to determine the direction of the herd?
Please contact your veterinarian if you have any questions regarding the health of your herd or other animals. Each operation is unique and the information in this column does not apply to all situations. This is not medical advice, but for informational purposes only.
Write Dr. Ken McMillan at Ask the Vet, 2204 Lakeshore Dr., Suite 415, Birmingham, AL 35209, or email [email protected]
(c) Copyright 2022 DTN, LLC. All rights reserved.