RESUMO
The influence exerted by natural antioxidants (Vitamin E or sodium ascorbate) was studied in various thermal treatments of semen and their effect on respiratory activity and membrane integrity during cryopreservation. Frozen bovine semen samples of diverse quality were employed in the presence and absence of antioxidants. Both in good-quality samples subjected to cold shock and in those of poor-quality standard-cooled, low superoxide dismutase activity was observed concomitantly with high malondialdehyde production; as regards oxygen uptake there was no evidence of mitochondrial coupling. In good-quality samples standard-cooled in the presence of antioxidants, greater superoxide dismutase activity, intact acrosome percentage and mitochondrial coupling were recorded as well as lower malondialdehyde production than in the controls. Natural antioxidants would seem to exert a protective effect on the membrane of the cryopreserved spermatozoon in samples from good-quality semen.
RESUMO
SOD activity and susceptibility to peroxidation on spermatozoa from frozen and fresh bovine semen were determined either in presence or not of synthetic (BHA) or natural (vitamin E) antioxidants. In sperm suspensions incubated with vitamin E, SOD activity was higher than in the control samples and the ones treated with BHA. It was found a highly significative correlation between malondialdehyde production and SOD activity. SOD activity could be used in bovine spermatozoa as a metabolic indicator of membrane integrity.
