Abstract: The aims of this study were to determine the effects of VC on protection of frozen-thawed X-sperm. The different concentration of VC (0.0, 2.0, 4.0, 6.0, 8.0 mg/mL) were added in ordinary dilution for experimentize. After thawed in thermostat-controlled waterbath about 37.5 ℃ for 30 s, then to detect the changes of sperm motility and the percent of integrity perforatorium and plasma membrane integrity. The results showed that the concentration of VC as 6.0 mg/mL, the sperm motility compare with the control group indicate no differences (P<0.05) when after frozen for 0 h, and it indicated differences (P<0.05) compare withd control group when after frozen for 1,2 and 3 h.when the concentration of VC as 4.0 mg/mL have the good effect on the rate of the sperm plasma membrane integrity. It indicate differences (P<0.05)compare with the control group. When frozen for 0 hour, and indicated no difference compare with che control group (P>0.05).When the sperm frozen for 1 h, and frozen for 2,3,4 h,the volue indicate difference compare with the control (P<0.05).When the concentration of VC as 4.0 mg/mL had the good effect on the rate of the sperm acrosome integrity. It indicated differences (P<0.05)compare with the control group. When frozen for 0 h, and indicate no differenced compare with che control group (P>0.05). When the sperm frozen for 1,3 h, and frozen for 2,4 h,the volue indicated no difference compare with the control group(P>0.05),but the volue was higher than control group. These results indicated that added the sufficient VC as 4 to 6 mg/mL in dilution of frozen semen can rise X-sperm quality effectily after frozen-thawed.

Key words: Holstein bull; frozen semen; VC; X-sperm