earticle

영어

Egg yolk (EY) has been widely used in semen extender as a cryoprotectant. However it contains a biologically hazardous compound. Therefore, the aim of this study was to investigate the effect of Polyvinyl Alcohol (PVA) as a chemically defined substitute for EY in dog sperm cryopreservation. Spermatozoa collected from five dogs were resuspended (1×108 cell/mL) with Tris extender 1 supplemented with 0 (control), 0.025, 0.05, 0.1, 0.2 or 0.3 g PVA. The extended spermatozoa were cooled to 4℃ for 1 h. The cooled spermatozoa were diluted (1:1) with Tris extender 2 containing 1 M glycerol and PVA concentrations used in the 1st dilution and then were loaded in 0.5 mL straws. The straws were kept at 4℃ for additional 30 min and were frozen using LN2 vapor. Sperm progressive motility was assessed immediately after thawing and post-thaw incubation at 24℃ for 20 min, respectively. Viability, acrosome integrity and reactive oxygen species(ROS) level were assessed following post-thaw incubation. As results, supplementation with PVA significantly(p<0.05) increased progressive motility compared to control group both immediately after thawing and post-thaw incubation. Moreover, the sperm progressive motility in 0.1g PVA group was significantly(p<0.05) higher than the rest of the PVA and control groups at post-thaw incubation. Although there were no significant differences in ROS level and viability among the groups, the acrosome integrity of spermatozoa in all PVA groups was significantly higher compared to the control group. We suggest that supplementation of Tris extender with PVA is effective for protecting dog spermatozoa during freezing with higher progressive motility and acrosome integrity. Therefore, PVA can be used as asubstitute for EY in the cryopreservation of dog spermatozoa.