By Frank Wardynski
Many beef cow-calf producers rely on multiple bulls to breed the cow herd without conducting fertility tests on bulls. Farms can have acceptable breeding rates with this strategy, however, this plan is not always successful and one missed pregnancy will have a negative economic impact. In instances where producers only have a few bulls, if the more dominant bull is infertile, he will usually dominate the breeding of cows by keeping less aggressive and smaller bulls from servicing cows.
Annually, about 20-25% of bulls do not pass breeding soundness exams. Breeding bulls can remain fertile with high-quality semen for 10 plus years. However, bulls may exhibit low fertility performance at any age. Low fertility can be caused by a number of factors including frost-damaged testicles, infection, poor nutrition and genetic predisposition. Younger bulls may exhibit breeding problems due to these same reasons. In addition, they may not have reached full sexual maturity or may have a small scrotal circumference.
Bulls can be tested for fertility utilizing a breeding soundness exam. During the exam they are inspected and observed for anatomical correctness and abnormalities such as penile warts, reproductive tract infection, scrotal circumference and semen quality. Semen quality is determined by collecting a semen sample to determine sperm cell motility, concentration and morphology.