Effect of Non-enzymatic Antioxidants in Extender on Post-thaw Quality of Buffalo (bubalus Bubalis) Bull Spermatozoa

The objective of the present study was to determine the effect of non-enzymatic antioxidants (vitamin C or E) in tris-citric acid buffer (TCA) on post-thaw quality of buffalo (Bubalus bubalis) bull spermatozoa. Split pooled buffalo bull ejaculates were diluted in TCA egg yolk glycerol extender containing either vitamin C (TCAC), vitamin E (TCAE) or without antioxidant (TCAN) at 37°C. Extended semen was cooled to 4°C in 2 h and equilibrated for 4 h at 4°C. Cooled semen was then filled in 0.5 ml straws at 4°C and frozen in programmable cell freezer. Thawing of semen was performed at 37°C for 30 seconds. Sperm motility, plasma membrane integrity and sperm morphology (acrosome integrity, head, mid-piece and tail abnormalities) of each semen sample were evaluated. Percentage of post-thaw spermatozoal motility assessed visually at 0 and 6 h and the post-thaw percentage of spermatozoa with intact plasma membranes at 0 h were higher (P<0.05) with TCAC and TCAE compared to control. However, the differences in both these parameters between the former two groups was non significant. The post-thaw percentage of spermatozoa with normal acrosomes was higher (P<0.05) in TCAE extender than control. Mean sperm abnormalities in samples cryopreserved with extender having TCAC, TCAE or TCAN were similar (P>0.05). In conclusion, non-enzymatic antioxidants, particularly vitamin E, in the tris citric acid extender may improve the quality of frozen-thawed buffalo bull spermatozoa.