Effect of antioxidants on the motility and viability of cooled stallion spermatozoa

The aim of the present study was to determine whether antioxidants in semen extenders help to maintain the motility and viability of stallion spermatozoa incubated for 48 h at 5 degrees C. Semen samples were collected from ten stallions and washed to remove the seminal plasma. Five antioxidant treatments (control, xanthurenic acid, glutathione, taurine and hypotaurine) were prepared in each of three different semen extenders (skimmed milk, skimmed milk + egg yolk, and cream gel extenders). The spermatozoa were suspended in 15 treatments (three extenders x five treatments). Sub-samples from each sample were analysed for sperm motility and viability at t = 0, 24 and 48 h. Significantly higher percentages of motile spermatozoa were maintained over 48 h in the skimmed milk + egg yolk extender compared with the other treatments. The percentage of progressively motile spermatozoa in the skimmed milk + egg yolk extender was significantly higher at t=0 and 24 h (P < 0.05) and tended to be higher after 48 h of incubation compared with the other treatments. Addition of xanthurenic acid to media maintained higher percentages of progressive motility and higher sperm velocities after 24 and 48 h incubation than did the other antioxidants (P < 0.05). The percentages of live spermatozoa in each of the three extenders were similar after 0 and 24 h incubation. However, the highest percentages of live spermatozoa were maintained in the skimmed milk + egg yolk extender and the lowest percentages of live spermatozoa were maintained in the cream gel extender after 48 h incubation (P < 0.05). Addition of the antioxidant xanthurenic acid to stallion sperm extender improved the motility of stallion spermatozoa incubated for 48 h at 5 degrees C compared with control media.