P-137: Improvement in Post-Thawed Ram Sperm Quality by Adding Cysteine in Soybean Lecithin Based Extender

Background: Ram sperm have a higher polyunsaturated fatty acids and a lower cholesterol/phospholipid ratio than other species which renders the sperm much more vulnerable to oxidative damage caused by reactive oxygen species (ROS). Oxidative stress can affects the integrity of cells at both the structural and sub structural levels. Therefore, a suitable antioxidant may prevent cryo-injuries and preserve sperm fertilizing ability after freezing-Thawing. So far, assessment of cysteine in ram cryopreservation medium based on soybean lecithin has not been studied. The aim of the current study was to evaluate the effects of cysteine (0, 5 and 10 mM) on the post-thawed sperm parameters, and acrosome status. Materials and Methods: Semen samples were diluted with extenders containing 5 or 10 mM cysteine which were based on Tris and soybean lecithin and then frozen. The sperm parameters were assessed after thawing for motility, viability and acrosome status. All experiments were repeated for seven times. Means of treatments were compared using Duncan’s multiple range tests by significant level of 0.05. Results: Results show that the addition of 10mM cysteine led to higher motility and viability compare to extender without cysteine (55.9 ± 1.56 and 60.5 ± 1.34 vs. 47.1 ± 1.56 and 54.1 ± 1.34). Unlike motility and viability, Cysteine had not significant effect on the membrane integrity, acrosome status and other CASA parameters like progressive motility, VCL, VSL, ALH, BCF, STR and LIN. When sperm parameters were compared between 5 and 10 mM cysteine, no significant were observed for all of sperm parameters. Conclusion: We conclude that addition of 10 mM cysteine to the ram sperm cryopreservation medium based on soybean lecithin led to production of higher motile and viable sperm so that produce sperm with higher fertilizing ability.