Effects of Equex STM and equilibration time on the pre-freeze and postthaw motility of equine epididymal spermatozoa

Abstract

Epididymal spermatozoa from castrated stallions were recovered, frozen, and thawed using techniques adapted from those used with ejaculated semen. An average of 7.93 × 10 9 spermatozoa were recovered per stallion, with a range of 1.45 to 16.82 × 10 9. Average prefreeze (postequilibration) motility was 32.0% ± 1.4 SEM. Prefreeze and postthaw motilities of epididymal spermatozoa were found to vary significantly between different stallions (P < 0.0001). No differences in prefreeze or postthaw motilities were seen between prefreeze equilibration times of 30 and 120 min. Prefreeze motility did rise, however, during the first 30 min of equilibration. Inclusion of the surfactant Equex STM a a Sodium and Triethanolamine Lauryl Sulfate, Nova Chemical Sales, Inc., Scituate, MA. in the extender had no significant effect on prefreeze nor postthaw motilities. In the motility of prefreeze sperm, interactions were found between the horse used and equilibration time and also between the horse used and the inclusion of Equex STM in the extender. No such interactions were seen with postthaw motilities. Postthaw motility averaged 6.4% ± 0.5 SEM or 20.7% ± 1.6 SEM of the prefreeze motility.