Effect of Vitamin E Supplementation during Buffalo Semen Cryopreservation on Sperm Characteristics and Oxidative Stress

The present study was undertaken to determine the effect of vitamin E supplementation to Tris-egg yolk diluent on post-thaw semen quality and oxidative parameters of buffalo bulls. Semen samples (eighteen ejaculates) were diluted in Tris-yolk egg medium without antioxidant (control group) and with vitamin E in different concentrations (0.5, 1.0, 1.5 and 2.0 mg/ml) and cryopreserved. After thawing, samples were subjected to selective semen parameters. Based on post-thaw selected sperm parameters, the concentration of 1.0 mg/ml vitamin E seemed to be most effective. Therefore, thirty ejaculates from same bulls were further collected, divided into two fractions [control and vitamin E supplemented (1.0 mg/ml)] and evaluated for semen characteristics and oxidative stress in post-thaw semen. The results revealed that progressive motility (29.0 ± 2.2 vs 24.1 ± 1.7%), sperm viability (63.2 ± 2.5 vs 56.7 ± 1.9%) and plasma membrane integrity (36.1 ± 2.2 vs 28.9 ± 1.4%) were significantly higher (P<0.05) in extender supplemented with vitamin E than in control. Regarding sperm kinematics, addition of vitamin E to extender significantly increased (P<0.05) VCL, VSL and STR when compared to control. Lipid peroxidation, as manifested by MDA production was significantly lower (P<0.05) in vitamin E supplemented than in control semen (187.0 ± 19.8 vs 245.5 ± 25.9 MDA μmole/10⁹ spermatozoa). It is, therefore, concluded that addition of vitamin E to extender prior to cryopreservation of buffalo bull semen protected sperm membrane against oxidative damage and improved the fertilizing potential of spermatozoa.