P-103: Effects of In Vitro Selenium Supplementation on Buffalo (Bubalus bubalis) Sperm Quality following Cryopreservation

Background: Artificial insemination is a valuable tool in genetic improvement programs and widely used breeding technique in farm animals. Semen processing and cryopreservation causes considerable damage to sperm DNA, motility apparatus, plasma membrane, acrosomal cap and thus, reduced fertility. Selenium is an integral part of glutathione peroxidase (GSH-Px), an enzyme which protects cell internal structures against free radicals. GSH-Px activity has been reported in the semen of several species including human, ram and bull. This experimental study was conducted to determine the effects of in vitro supplementation of sodium selenite (Na2Se03) on sperm parameters of semen. Materials and Methods: In the study, a total number of 25 semen ejaculates were collected from five healthy buffalo breeding bulls (2-4 years age) kept at Buffalo Breeding Center of north- west of Iran. Each ejaculate was split into 6 portions and diluted with tris-egg yolkglycerol extender containing 0 (control), 0.5, 1, 2, 4 and 8 μg/mL sodium selenite. After equilibration, semen parameters (motility, viability, membrane integrity and DNA fragmentation) were estimated. Then, semen was freezed in liquid nitrogen and the same parameters, as well as total antioxidant capacity (TAC) of the frozenthawed semen, were estimated. Results: The results showed that adding 1 and 2 μg/mL selenium to the extender significantly (p<0.05) increased the sperm quality of equilibrated and frozen semen of buffalo bulls as compared to the non-supplemented control group; with higher values obtained after adding 2 μg /ml selenium. Selenium at concentrations of 4 and 8 μg/ mL had a deleterious effect on sperm parameters. Conclusion: This study indicates that in vitro selenium supplementation may help to ameliorate negative effects of semen storage on characteristics of sperm quality. However, selenium exerts its effects in a dose-dependent manner and exposure to high levels can cause deleterious effects.