Effect of alpha-tocopherol acetate and ascorbic acid in extender on quality of Zebu bull spermatozoa

The experiments were designed to determine the effect of alpha-tocopherol acetate and ascorbic acid in extender on post-thaw motility, plasmalemma functionality, viability and chromatin damage of Zebu bull spermatozoa. Semen collected from three bulls of Sahiwal breed (Bos indicus) was diluted with tris-citric acid extender either containing alpha-tocopherol acetate or ascorbic acid at 0.5, 1.5, 2.5 and 3.5 mM or without any supplement (control) and cryopreserved. For each extender, thawing of three semen straws was performed at 37 degree C for 30 seconds for the assessment of sperm quality parameters. Sperm motility (%) remained similar in extenders containing alpha-tocopherol at 0.5. 1.5, 2.5 mM and control. Sperm plasmalemma functionality (%) was recorded higher (P less than 0.05) in extender containing 0.5, 1.5 and 2.5 mM alpha-tocopherol acetate than control. Sperm viability (%) was observed higher (P less than 0.05) in extender containing 0.5 mM alpha-tocopherol acetate. Sperm chromatin damage was similar (P greater than 0.05) in all experimental extenders containing alpha-tocopherol acetate and control. Extenders containing ascorbic acid 0.5, 1.5, 2.5, 3.5 mM did not improve sperm motility, plasmalemma functionality, viability and chromatin integrity. In conclusion, alpha-tocopherol acetate (0.5 mM) in extender improved the plasmalemma functionality and viability of frozen-thawed Zebu bull spermatozoa.