Sperm selection by Capripure® density-gradient centrifugation versus the dextran swim-up procedure in wild mountain ruminants

This study compares the effectiveness of two methods of sperm selection – Capripure® density-gradient centrifugation (DGC) and dextran swim-up (DSU) – in semen samples from Iberian ibex (Capra pyrenaica) and European mouflon (Ovis musimon). During the increasing photoperiod, Capripure® DGC improved the percentage of sperm with progressive motility (P < 0.05) in ibexes, and selected 60.6% of the initial total number of spermatozoa contained in the ejaculate samples. In mouflon, Capripure® DGC selection was unaffected by photoperiod, had no influence on any sperm variable, and selected 47.8% of the initial total number of mouflon spermatozoa in ejaculate samples. Photoperiod had no influence on the effectiveness of DSU in either ibexes or mouflons. In the ibexes, DSU reduced (P < 0.05) the percentage of sperm cells with morphological abnormalities, but only selected 11.3% of the initial total number of spermatozoa in ejaculate samples. In the mouflons, DSU had no significant influence on any sperm variable, and selected 27.8% of the initial total number. Capripure® DGC improved ibex and mouflon sperm motility (P < 0.05) following 30 min and 2 h of post-centrifugation, stress-inducing incubation, respectively. In both ibexes and mouflon, sperm cells showing non-progressive motility were found after only 20 h of post-centrifugation incubation following Capripure® DGC selection. In conclusion, Capripure® DGC would seem a useful method for selecting the best spermatozoa from both ibex and mouflon ejaculates.