The study investigated sperm membrane integrity (as a measure of sperm viability) and sperm motility in spermatozoa taken from different portions of the ejaculate, namely the first 10 ml (P1) of sperm-rich fraction (SRF) and from the rest of the ejaculate up to the appearance of gel (P2), both before and after centrifugation on a single layer of Androcoll-P-Large (SLC). Thus there were 4 treatment groups: P1, P2, SLC P1 and SLC P2. Sperm motilities were not different between the various treatment groups, except that the SLC samples had higher linear + non-linear motility than the non-SLC-selected samples. Sperm membrane integrity, in contrast, was significantly higher in P2 than in P1 (P < 0.001), and was also higher in both SLC-selected groups than in the uncentrifuged groups (P < 0.001). There was a significant correlation between membrane integrity and linear + non-linear motility (P < 0.001). These results indicate that the spermatozoa found in P2 have better membrane integrity than those in P1 when used as fresh spermatozoa, and furthermore, that SLC selects the most robust spermatozoa regardless of their origin in the ejaculate. Thus, in situations where P1 is collected separately for sperm cryopreservation purposes, the remainder of the SRF could be used for fresh AI doses, particularly where SLC can be used to select the most robust spermatozoa. These findings have practical importance for the swine insemination industry.
