Antioxidative effects of cysteamine, hyaluronan and fetuin on post-thaw semen quality, DNA integrity and oxidative stress parameters in the Brown Swiss bull.

The aim of this study was to compare the effectiveness of antioxidants including cysteamine (2.5, 7.5 mm), hyaluronan (0.25, 1 mg ml(-1) ) and fetuin (5, 10 mg ml(-1) ) in the freezing of Brown Swiss bull semen. The best percentages of CASA motilities were achieved with 10 mg ml(-1) of fetuin and 2.5 mm of cysteamine. For sperm morphology, 10 mg ml(-1) of fetuin and 2.5 mm of cysteamine had better protective effects (P < 0.001). The results of hypo-osmotic swelling test showed that the percentage values of membrane integrity in all the groups, excluding that supplemented with 5 mg ml(-1) of fetuin, were higher than those of the control group (P < 0.001). Results obtained for the DNA damage of sperm cells demonstrated that 0.25 mg ml(-1) of hyaluronan, and 2.5 and 7.5 mm of cysteamine led to lower rates of spermatozoa with damaged DNA, compared with the control group (P < 0.001). The maintenance of superoxide dismutase and glutathione peroxidase antioxidant activities following freeze-thawing with 2.5 and 7.5 mm of cysteamine and 10 mg ml(-1) of fetuin was demonstrated to be at a higher level in comparison with the control group (P < 0.001). Malondialdehyde formation was found to be lower in the groups supplemented with 0.25 mg ml(-1) of hyaluronan and 7.5 mm of cysteamine after the freeze-thawing process (P < 0.001).