L-Cysteine improves antioxidant enzyme activity, post-thaw quality and fertility of Nili-Ravi buffalo (Bubalus bubalis) bull spermatozoa

The effects of l-cysteine in extender on antioxidant enzymes profile during cryopreservation, post-thaw quality parameters and invivo fertility of Nili-Ravi buffalo bull spermatozoa were studied. Semen samples from 4 buffalo bulls were diluted in Tris-citric acid-based extender having different concentrations of l-cysteine (0.0, 0.5, 1.0, 2.0 and 3.0mm) and frozen in 0.5-ml French straws. The antioxidative enzymes [catalase, super oxide dismutase and total glutathione (peroxidase and reductase)] were significantly higher (P<0.05) at pre-freezing and post-thawing in extender containing 2.0mm l-cysteine as compared to other groups. Post-thaw total motility (%), progressive motility (%), rapid velocity (%), average path velocity (ms(-1)), straight line velocity (ms(-1)), curvilinear velocity (ms(-1)), beat cross frequency (Hz), viable spermatozoa with intact plasmalemma (%), acrosome and DNA integrity (%) were higher with the addition of 2.0mm l-cysteine as compared to other groups (P<0.05). The fertility rates (59 versus 43%) were higher (P<0.05) in buffaloes inseminated with doses containing 2.0mm of l-cysteine than in the control. In conclusion, the addition of 2.0mm l-cysteine in extender improved the antioxidant enzymes profile, post-thaw quality and invivo fertility of Nili-Ravi buffalo bull spermatozoa.