– Dr. Les Anderson, Extension Professor, University of Kentucky
Many producers with spring calving herds just turned out their bulls. In the May Off the Hoof, we reminded everyone to subject their herd bulls to a breeding soundness exam (BSE). A BSE is the best insurance we have available to ensure we don’t turn out a bull that is infertile or incapable of breeding cows. However, the BSE does not indicate if the bull is willing to breed cows. I was reminded of this very recently in the herd that I used for the “I bought a farm” YouTube video series. To get these heifers bred, we synchronized them for AI and then turned out a mature bull that had passed a BSE. When I inseminated these heifers, the weather turned very poor (middle of December) and the estrus response rate in the heifers was low, so I wasn’t expecting high conception rates to AI. Just to get an idea of how well we did, I spent some time in the pasture watching for return heats. As I expected, several heifers had return heats but what really stuck out was the bull was NOT breeding them. Some of the heifers were jumping on the bull and he seemed disinterested. I was concerned about the bull and told the owner that he needed to consider finding another bull. I could not assure him the bull was not getting the job done as research has shown that mature bulls will only breed a female in heat 1-3 times even though she is in heat for as long as 12 hours. This bull however showed absolutely no interest. For a variety of reasons, the owner decided to not get another bull. Pregnancy rates were only 61% in this group of heifers. The decision may have cost this producer significantly.
Bottomline: keep an eye on your bull to make sure he is working. Multiple return heats indicate a bull that is not getting females pregnant. If possible, replace the lazy bull. It will cost some money to make a switch, but this cost is likely much lower than the cost of open females.