David Freeman, Equine Extension Specialist, Oklahoma State University,
Farms using live cover record the number of daily breedings for each stallion. Those using artificial insemination document semen evaluation. Semen evaluation records include:
- Semen volume
- Concentration
- Morphology
- Motility
These factors determine the semen volume necessary for an insemination dose. Motility, the number of moving sperm, is estimated using a microscope. Concentration is measured by a spectrophotometer. A morphological assessment estimates the percent of abnormal sperm.
Review of daily records establish a stallion’s average semen production throughout the breeding season. Knowing the expected level of semen production determines the number of mare bookings. Unexpected changes in quantity or quality of semen can indicate health problems that need immediate attention.

