Stallion sperm quality after combined ejaculate fractionation and colloidal centrifugation

Abstract

This study investigated the possible additive benefit of ejaculate fractionation and colloidal centrifugation on stallion sperm quality. Using an open-end artificial vagina, the sperm-rich fraction (FRAC-1) was separated from the rest of the ejaculate (FRAC-2) and a third sperm sample representing the combined ejaculate was reconstituted post-ejaculation (RAW). Each semen sample was processed for colloidal centrifugation. The percentage of abnormal spermatozoa was 17.8 ± 7.0% in RAW and 14.6 ± 9.5% in FRAC-1 but decreased to 11.4 ± 4.7% and 9.6 ± 6.9% respectively, after colloidal centrifugation. A sperm DNA fragmentation index of 10.9 ± 5.1% was observed in RAW and 7.5 ± 2.4% in FRAC-1 semen collected with the AV but this decreased to 7.8 ± 2.8% and 5.2 ± 2.3% after colloidal centrifugation. The rate of increase in sperm DNA fragmentation during the first 6 h of incubation at 37 ºC was 1.8 ± 0.9% per hour in RAW semen and 2.0 ± 2.0% per hour in FRAC-1 but this significantly decreased to 1.3 ± 1.4% and 0.9 ± 0.8% respectively after colloidal centrifugation. While stallion seminal characteristics can be improved using colloidal centrifugation, further enhancement is possible if the ejaculate is initially fractionated