The fertility of the herd bull is essential to a successful cow-calf operation. In many respects, it is more of a concern than the fertility of a single cow. Sub-fertile bulls create lower calving rates and can be responsible for poor herd-weaning weights: For every heat cycle a female fails to conceive, there is a corresponding decrease in calf weaning weight from 25 to 45 pounds because of a younger calf being weaned. It does not take long to realize that poor fertility or infertility of a bull can be extremely expensive to the cow-calf producer.