Cryoprotective effect of melatonin supplementation on post-thawed rooster sperm quality.

Reactive oxygen species (ROS) and free radicals are one of the major detrimental factors that can negatively affect the quality of sperm during cryopreservation. Melatonin is an effective antioxidant and free radical scavenger in various cells. In this study, therefore, the aim was to evaluate the post-thawed quality of spermatozoa after cryopreservation of rooster semen in freezing extender supplemented with melatonin. Semen samples from seven Green-legged Partridge roosters were pooled and diluted with EK extender supplemented with 10-3, 10-6, or 10-9 M melatonin (control sample was prepared without supplementation with melatonin), and the pooled sample was subjected to cryopreservation. Post-thawed sperm motility was determined using the IVOS system, whereas plasma membrane status, acrosome integrity, mitochondrial activity, lipid peroxidation, chromatin status, and apoptotic-like changes were determined using fluorochromes and flow cytometry. Results, indicate post-thaw motile sperm cell count was greater (P < 0.05) in the frozen samples supplemented with melatonin (10-3 and 10-6 M) than the control sample. Although no significant differences were observed in post-thawed acrosomal integrity, plasma membrane integrity and mitochondrial activity were greater (P < 0.05) in samples frozen with melatonin (10-3 and 10-6 M) than that of the control sample. In addition, with supplementation of melatonin there was a decrease (P < 0.05) in the amount of lipid peroxidation, DNA fragmentation, and apoptotic-like changes after thawing. These results indicate there is a positive effect of melatonin supplementation in rooster semen freezing extenders on post-thaw sperm quality.