Effects of Antioxidants on the Quality of Hypothermic Preservation and Frozen-thawed Equine Semen

This study was aimed to evaluate the effects of various antioxidants, namely glutamine (0.015 g/mL), glycine (0.019 g/mL), cysteine (0.024 g/mL), methionine (0.015 g/mL), taurine (0.063 g/mL), vitamin C (0.4 mg/mL), vitamin E (0.5 mg/mL) and melatonin (0.001 mg/mL) on equine sperm quality after chill or freeze-thaw.Semen were collected from 6 adult thoroughbred stallions, INRA82 was used as the base extender (control group), adding INRA82 with different antioxidants was used in experimental group. Assess the effect of antioxidants on semen by detecting motion parameters after storage at 5℃ for 48 h. Motion parameters, plasma membrane integrity (PMI) and mitochondrial membrane potential were used to evaluate semen quality after thawing. The extender supplemented with 25 mmol/L taurine led to higher TM and PM, and supplemented with 0.4 mg/mL vitamin C obtained significant higher PM compared with control group (P<0.05) after storage at 5℃ for 48 h. The freeze extender supplemented with 0.5 mg/mL vitamin E or 0.015 g/mL methionine significantly increased the mitochondrial membrane potential compare with control group (P<0.05). No significant differences were observed for PMI and acrosomes integrity rate after frozen-thawed (P>0.05), but there was a trend that PMI of adding methionine and glycine group was higher than control group. The results suggested that extender supplemented with taurine and vitamin C could improve the semen preservation effect, and the extender supplemented with methionine could improve plasma membrane integrity, mitochondrial membrane potential of thawing sperm, and also could prolong the survival time of frozen thawed sperm.