Effects of epididymis cold storage on frozen-thawed epididymal sperm quality in tomcats (Felis catus)

The effect of cold storage of testes and epididymides at 4 °C for 12 h on the cryopreservation capacity of epididymal feline sperm was evaluated. Ten domestic cats were castrated, and testes and epididymides collected. Specimens were randomly assigned to two groups: in Group A, epididymal samples were immediately processed and frozen in 0.25-ml straws; in Group B, both testes and epididymides were maintained in saline at 4 °C for 12 h and sperm was then processed and frozen. Motility, morphology, acrosome status, sperm viability and DNA integrity were assessed in epididymal sperm samples before freezing (baseline), at thawing (0 h) and 6 h post-thawing (6 h). Although values were lower in Group B, no significant intergroup difference was observed for any of the parameters tested either at baseline or at 0 h. However, significantly higher values (P < 0.05) were observed in Group A at 6 h for total sperm motility (29.0 ± 2.4% vs 13.0 ± 4.3%), sperm viability (35.2 ± 5.4% vs 15.4 ± 1.4%) and normal morphology (47.6 ± 0.8% vs 40.0 ± 2.1%). It was observed that motility and acrosome status of epididymal sperm are the most sensitive parameters when both types of sperm samples (from fresh epididymis or from 12 h cold-stored epididymis) are frozen-thawed. When sperm quality was assessed 6 h after thawing, spermatozoa precooled in the epididymides showed significantly lower values for motility, viability and morphology than spermatozoa from fresh epididymal samples.