Abstract
This experiment was carried out to investigate the renditions to maintain good post-thaw motility and viability of canine spermatozoa when the semen was frozen using methanol. The semen from two male dogs which had been proven to be fertile in the previous one year was treated with different compositions of semen diluent and was frozen at different freezing temperatures, When canine semen was frozen at-2$0^{\circ}C$, -6$0^{\circ}C$, or -8$0^{\circ}C$, the spermatozoa frozen and stored at -2$0^{\circ}C$ showed very low post-thaw motility and viability from day 2 to 7 and showed no viability since day 15 after freezing. The spermatozoa frozen and stored at -6$0^{\circ}C$ or -8$0^{\circ}C$ showed higher post-thaw motility and viability on day 2, 1, 15 and 30 after freezing than that frozen and stored at-2$0^{\circ}C$(p<0.01), with no difference between two groups. Among different composition groups of the semen diluents of control(tris + egg yolk + glycerol), egg yolk-free, 히ycerol-free, and tris-free, Prior to freezing, the egg yolk-free diluent showed significantly love. motility and viability than the other diluents(p<0.05). On each thawing day (from day 2 to 15 after freezing), control group showed considerably higher motility and viability than the other groups(p<0.01). The canine spermatozoa frozen and stored at -6$0^{\circ}C$ and -8$0^{\circ}C$ showed gradual decrease of motility from day 2 to 30 after freezing and the spermatozoa of these two groups thawed on day 30 showed considerably love. motility than those thawed on day 2 after freezing, respectively(p<0.01). These results indicate that the freezing temperature of either -6$0^{\circ}C$ or -8$0^{\circ}C$ can be applicable to the freezing method using methanol and also all of the components of the semen diluent including cryoprotectant, buffer and cold-shock buffer are very important to maintain motility and viability of canine spermatozoa in the freezing and thawing procedure.
