Effects of curcumin and dithioerythritol on frozen-thawed bovine semen.

The aim of this study was to determine the effects of curcumin and dithioerythritol added into bull semen extender on sperm parameters, lipid peroxidation, total glutathione and antioxidant potential levels of bull spermatozoa following the freeze/thawing process. Twenty-seven ejaculates obtained from three bulls were included in the study. Each ejaculate that was splitted into five equal groups and diluted in a Tris-based extender containing curcumin (0.5 and 2 mM), dithioerythritol (0.5 and 2 mM) and no additive (control) was cooled to 5 °C and frozen in 0.25-ml French straws. The extender supplemented with 0.5 mMdose of curcumin led to lower percentage of total abnormality (20.40 ± 2.36%) when compared to the control (30.60 ± 1.47%, P < 0.05). Curcumin and dithioerythritol at 0.5 mM provided a greater protective effect in the membrane functional integrity (54.40 ± 2.09% and 50.00 ± 2.68%), in comparison with control (37.20 ± 1.77%, P < 0.001). Supplementation with antioxidants did not significantly affect the lipid peroxidation and antioxidant potential levels, while the maintenance of total glutathione levels in curcumin 0.5 mM was demonstrated to be higher than that of control, following the freeze/thawing (P < 0.05). Supplementation with these antioxidants prior to the cryopreservation process may be recommended to facilitate the enhancement of sperm cryopreservation techniques.