The effect of different levels of glutathione and superoxide dismutase on some characteristics of bull spermatozoa after freezing

The aim of this study was to determine the effects of adding different levels of superoxide dismutase (SOD) and reduced glutathione (GSH) antioxidants before freezing on motility, total progressive motility, viability and positive response to hypo-osmotic swelling test (HOST) parameters after Bull semen was frozen. In this study, four bulls aged 4-5 years were used and 20 times the semen collection (5 ejaculates per bull) was performed. The samples were frozen, after addition of the superoxide dismutase (100 and 150 IU / ml) and GSH (5 and 7.5 mM) antioxidants was added to Tris - egg yolk extender. After thawing samples, the total and progressive motility, sperm viability and positive response to the HOST parameters were determined at zero and 2 hours of incubation. Adding superoxide dismutase and GSH antioxidant levels did not reveal significant differences between treatments in any of the semen parameters in the initial hour of incubation after thawing. 2 h incubation of post-thawed semen samples containing superoxide dismutase (100 IU/ml) significantly improved total motility, viability and membrane integrity of the sperm (P< 0.05). Also, in samples containing superoxide dismutase (150 IU/ml), sperm membrane integrity was maintained (P<0.05). In the semen samples with antioxidant GSH (5 mM), total motility and membrane integrity of the sperm are considerably improved after tawing (P< 0.05). This study showed that using of superoxide dismutase and GSH antioxidants as freezing semen extender additives can be used to improve post-thawed bull semen quality.