It’s hot and it hurts bulls’ fertility. A bull’s ability to produce quality quantities of semen is important to successful breeding and rebreeding programs. If heat stressed, bulls could have lower sperm concentrations than normal. Plus, heat stressed bulls produce semen of lower quality than bulls who weren’t heat stressed.
Source: Progressive Cattle, July 19, 2022. Link. But the issues of heat stress did not stop with the semen. Research showed that if successful fertilization occurred with a heat-stressed bull, the cleavage and blastocyst rates on day seven and eight were lower when fertilized with heat-stressed semen. . . . Overall results indicate that semen samples collected from heat-stressed bulls impacted overall embryonic health and development.