PAKISTAN JOURNAL OF ZOOLOGY, vol.47, no.6, pp.1571-1577, 2015 (SCI-Expanded)
The antioxidant effects of ascorbic acid at different inclusion rates were evaluated upon semen (n=150) from mature Sahiwal cattle bulls (Bos indicus, n = 6) in summer season. The semen was diluted in Tris-citrate egg yolk extender containing different levels (0.0, 1.0, 2.0, 3.0, and 4.0 mg/mL) of ascorbic acid at 37.0 degrees C. Semen was cryopreserved at -196 degrees C in 0.5 mL French straws. Semen straws were thawed at 37 degrees C to assess the spermatozoa indices in terms of motility, viability, plasma membrane and acrosomal integrity under phase-contrast microscope. Supravital staining, hypo-osmotic swelling test and normal acrosomal reaction analysis tests were also performed for viability, plasma membrane and acrosomal integrity, respectively. The data were subjected to one way ANOVA. The results revealed significant improvement (P< 0.05) in post thaw sperm quality in terms of motility, vitality, acrosomal and plasma membrane integrity by the increasing concentrations of ascorbic acid (1.0, 2.0, 3.0, 4.0 mg/mL) in semen extender. Quality parameters were higher (P< 0.05) when 3.0 mg/mL of ascorbic acid was added in semen extender followed by 2.0 and 4.0 mg/mL. In conclusion the addition of ascorbic acid at the rate of 3.0 mg/mL in the semen extender may improve the semen quality of Sahiwal cattle bull.