Influence of various antioxidants added to TCM-199 on post-thaw bovine sperm parameters, DNA integrity and fertilizing ability.

Supplementation of the semen extender with antioxidants did not produce any significant effect on CASA and progressive motilities and sperm motility characteristics, in comparison to the control group (P > 0.05). For sperm acrosome and total abnormalities, TCM-199 supplemented with cysteine (2.60 ± 0.24% and 4.80 ± 0.20%), glutamine (2.80 ± 0.20% and 6.40 ± 0.40%), carnitine (2.60 ± 0.24% and 6.00 ± 0.63%) and methionine (3.40 ± 0.51% and 9.20 ± 0.86%) at doses of 2 mM provided a better protective effect, compared to that of the controls (8.00 ± 0.44 and 15.60 ± 1.895). As regards sperm membrane integrity, supplementation with 2 mM of glutamine and methionine (56.00 ± 1.70% and 62.40 ± 1.78%, respectively) resulted in higher rates, when compared to the control group (41.40 ± 4.74%). According to the results of the COMET assay, only the use of TCM-199 supplemented with 2 mM of cysteine reduced DNA damage and resulted in percentages of sperm with damaged DNA (2.17 ± 0.18%) lower than those of the control group (3.16 ± 0.32%) (P < 0.001). For pregnancy rates, there were no significant differences among the extender groups (P > 0.05).