Superoxide Dismutase in Extender Improves the in vitro Quality and in vivo Fertility of Cryopreserved Water Buffalo (Bubalus bubalis) Spermatozoa.

Background: Superoxide dismutase (SOD) as an antioxidant in semen extender may be used for the cryopreservation of buffalo spermatozoa and in vivo fertility.
Objective: This study was aimed to evaluate the effects of SOD (SOD1, 100 IU/mL; SOD2, 200 IU/mL; SOD3, 300 IU/mL) and control (0.0) in Tris citric acid extender on in vitro quality and in vivo fertility of cryopreserved water buffalo bull spermatozoa.
Materials and Methods: Semen collection was carried out on a weekly basis (four bulls, three replicates, and n = 24 ejaculates). The conventional freezing of semen loaded straws (0.5 mL) was undertaken by placing them horizontally on a steel rack inside a Styrofoam box for 10 min containing liquid nitrogen (LN2) vapours, and plunging into a liquid nitrogen tank (-196 °C) for storage, followed by thawing at 37 °C for 30 s and analysis by computer-assisted sperm analyzer (CASA) and other assays.
Results: At post-dilution, the acrosome integrity (ACR-I, %) was significantly improved (P < 0.05) in extender supplemented with SOD3 as compared to other experimental groups. In addition, DNA integrity (DNA-I, %) was significantly higher (P < 0.05) in SOD1 and SOD3 compared to SOD2 and control. At post-thawing, the mean values of sperm progressive motility (PM, %), average path velocity (VAP, µm/s) and straight line velocity (VSL, µm/s) were significantly higher (P < 0.05) in extender supplemented with SOD3 compared to the control. At post-thawing, mean values of subjective motility (SM, %), plasma membrane integrity (PMI, %) and ACR-I were significantly higher (P < 0.05) in extender supplemented with SOD3 compared to the control. At post-thawing, sperm DNA-I was significantly higher (P < 0.05) in extender supplemented with all SOD doses compared to the control in a dose-dependent manner. The in vivo fertility rate (%) was significantly higher with SOD3 compared to the control (68.2 % vs. 49.5 %).
Conclusion: The supplementation of SOD3 (300 IU/mL) in Tris citric acid extender improves both in vitro quality and in vivo fertility of buffalo bull spermatozoa.