Post-thaw motility and longevity of motility of imipramine-induced ejaculates of pony stallions

Imipramine-induced ex copula ejaculates (11) and fractionated in copula ejaculates were collected from each of 5 pony stallions for freezing in 5-ml straws (6), using a modified Kenney glucose skim-milk extender (2). Initial post-thaw total and progressive motilities and daily post-thaw total and progressive motilities, as well as the number of days to reach 0 progressively motile spermatozoa, were also similar for the 2 methods of collection. The percentage of morphologically normal spermatozoa both before freezing and after thawing were also similar for in copula and ex copula ejaculates. Consistent with previous work (11), imipramine-induced ejaculates were of extremely high sperm concentration and low volume compared with those of in copula ejaculates. In this study, imipramine-induced ejaculates were of significantly higher concentration of sperm and lower volume than fractionated (first 2-3 jets) in copula ejaculates. These results suggest that imipramine-induced ejaculates may be suitable for cryopreservation. Breeding trials are necessary to evaluate actual fertility of semen.