Cooled-shipped semen is one of the most common breeding modalities in the equine industry. This sperm, however, is generally less fertile than less-commonly used fresh semen.

To help veterinarians evaluate a stallion’s potential as a cooled-shipped semen candidate, researchers at Texas A&M University’s College of Veterinary Medicine and Biomedical Sciences took a closer look at sperm quality’s relationship to fertility. They sought to identify sperm quality endpoints that would indicate when reduced fertility was associated with sperm quality. Charles Love, DVM, PhD, Dipl. ACT, associate professor in equine theriogenology, presented their results during the 2014 American Association of Equine Practitioners Convention, held Dec. 6-10 in Salt Lake City, Utah.

"Currently, there are no guidelines available that can discern sperm quality that is associated with good fertility from sperm quality associated with lesser fertility," Love said.

His study involved 459 ejaculates from 130 Paint and Quarter Horse stallions with an average age of 12. The ejaculates were collected and then shipped to an embryo transfer facility for artificial insemination. Love and his colleagues measured fertility using embryo recovery rate from 196 mares