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The antioxidant systems of superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), and glutathione peroxidase (GSH–Px) are important in maintaining sperm motility and viability. The purpose of this study was to determine the effects of varyilig doses of trehalose on in vitro semen quality variables and antioxidant activities of frozenthawed bovine semen. The semen samples, diluted with an extender containing trehalose (0, 25, 50, 100, and 200 mM), were evaluated. The extender supplemented with 100 mM trehalose exhibited the greatest percentages of sperm motility, acrosomal membrane integrity, and plasma membrane integrity in comparison with the control group (P < 0.05). No difference was observed for sperm motility between trehalose 50 and 100 mM groups (P > 0.05). Extender supplemented with trehalose did not affect SOD levels. Compared with the other groups, CAT was greater with the supplementation of trehalose at 100 and 200 mM (P < 0.05). The extender supplemented with trehalose had enhanced GSH–Px activity compared with the control group (P < 0.05). However, increasing the doses of trehalose (100, 200 mM) decreased GSH–Px activity, compared with 50 mMtrehalose (P < 0.05). Compared with the other groups, trehalose at the concentration of 25 and 50 mM increased GSH activity (P < 0.05). The application of 200 mM trehalose produced the least amount of GSH activity among all of the groups (P < 0.05). In conclusion, extender supplemented with trehalose reduced the oxidative stress induced by freeze–thaw and improved measures of bovine semen quality. The antioxidant characteristics of trehalose may be related to its effectiveness in membrane cryopreservation. Further studies are required to obtain more concrete results on the determination of lipid peroxidation and antioxidant capacities of trehalose in cryopreserved bovine semen. [ABSTRACT FROM AUTHOR]

The present study aimed to investigate the effects of vitamin B supplementation on standard bovine semen quality parameters and anti-oxidative enzyme activities. Vitamin B was supplemented at concentrations of 1.25, 2.5, 3.75 and 5.0 mg/ml to bovine semen cryoprotective medium. The results indicated that the motility and straight line velocity, curvilinear velocity, mean coefficient, velocity of the average path values of sperm supplemented with 2.50 mg/ml vitamin B were significantly higher than that of other groups (p < 0.05). No significant difference was observed for linearity index, lateral head displacement values and the percentage of grade A spermatozoa between the extenders containing 2.50 and 3.75 mg/ml vitamin B (p > 0.05). The percentages of acrosome-intact and plasma membrane-intact spermatozoa were significantly improved (p < 0.05) by supplementing with 2.50 mg/ml vitamin B. The results of biochemical assay revealed that vitamin B supplementation did not cause significant changes in superoxide dismutase levels compared with control (p > 0.05). However, the catalase levels were higher in the treatment supplemented with vitamin B at 2.50 mg/ml, when compared with other groups (p < 0.05). The extender supplemented with vitamin B significantly decreased glutathione peroxidase activity compared with the control (p < 0.05). The supplementation of 3.75 mg/ml vitamin B caused the highest value of glutathione reductase activity, compared with other groups (p < 0.05). In conclusion, the extender supplemented with vitamin B could reduce the oxidative stress provoked by freezing-thawing and improve bovine semen quality. Further studies are required to obtain more concrete results on the determination of lipid peroxidation and antioxidant capacities of vitamin B in cryopreserved bovine semen. [ABSTRACT FROM AUTHOR]