The decision to manage a subfertile stallion non-conventionally is “based on the condition of farm economics or despair, or more appropriately, the last hope before retiring the stallion,” said Irwin K.M. Liu, DVM, PhD, a professor in the Department of Population Health and Reproduction in the University of California, Davis, School of Veterinary Medicine. Liu brought to the table suggestions for managing stallions with declined fertility at the Hagyard Bluegrass Equine Symposium, held Oct. 20-23, 2004, in Lexington, Ky.

“Most of you realize that our understanding and management of subfertile mares has substantially increased,” he said. “Assisted reproduction technology has made a significant impact on pregnancy rates in subfertile mares,” and has the potential to help subfertile stallions as well.  But not many strategies have helped the subfertile stallion under natural cover conditions and requirements.

Liu explained that testicular degeneration is often–but not always–associated with age and declining pregnancy rates, and it is highly correlated with low sperm concentrations and abnormal sperm pathology. Testicular degeneration varies from stud to stud. “Clearly each management strategy is based on the individual cause of subfertility,” said Liu.

The normal sperm of young subfertile stallions  appear to be more fertile than the normal sperm of older subfertile stallions, so managing an older stallion will likely be more intensive