Ascorbic acid or pyruvate counteracts peroxidative damage in boar sperm cryopreserved with or without alpha-tocopherol

Ejaculates of four crossbred boars were frozen with or without 200 mu g/mL of alpha-tocopherol. Frozen samples were then thawed in the extender containing either ascorbic acid (2.5, 5 or 10 mM) or pyruvate (1 or 5 mM) to obtain the samples in which sperm quality parameters and lipid peroxidation level were evaluated. Ascorbic acid decreased lipid peroxidation in a dose-dependent manner and increased post-thaw sperm motility. The addition of pyruvate decreased lipid peroxidation level without improving sperm quality parameters. Although the addition of ascorbic acid or pyruvate did not show a synergic effect with alpha-tocopherol, the decrease of lipid peroxidation observed when the antioxidants were added to the thawing extender could be indicating a protective effect on the sperm plasma membrane from peroxidative damage. Since alpha-tocopherol protects from the lipid peroxidation and improves the sperm motility, it would be considered as the recommended antioxidant to use in boar sperm cryopreservation to extend the time of storage for the use in commercial applications.