P-133: Effect of Thawing Rate on Kinetic Parameters of Frozen - Thawed Buffalo Spermatozoa Extended in Tris - Egg Yolk

Background: Optimal thawing rate is critical for quality and fertilizability of frozen -thawed spermatozoa. Kinetic parameters are the most important factors which are affected by thawing rate so, that have close relation between kinetic parameters and fertility of the spermatozoa. Tris - egg yolk have been widely used for cryopreservation of the buffalo and other species semen. According to our findings no studies have examined the influence of different thawing rate on kinetic parameters of buffalo spermatozoa. Therefore, the objective of the current study is to evaluate the effect of different thawing rate on post thaw kinetic parameters of buffalo spermatozoa extended in Tris - egg yolk. Materials and Methods: Fifteen ejaculations of five mature buffalo semen were diluted with tris -citrate-egg yolk extender and frozen .Three straws of each bull thawed at 37°C for 30 seconds, 50°C for 15 seconds and 70°C for 7 seconds then placed in makler chamber and analyzed with computer assisted sperm analyzer system (CASA) immediately and after 2 hours incubation. Results: Semen thawing in 50°C significantly increased the progressive motility (PM) and curvilinear velocity (VCL) (29.8 ± 4.00% and 59.40 ± 7.30 μm/s respectively) at 0 hour when it compared to 37°C (19.08 ± 4.63% and 47.29 ± 3.0 μm/s). There was no significant difference in PM between 50°C and 70°C (26.92 ± 9.22%) while VCL was significantly improved in 50°C in comparison with 70°C (46.99 ± 7.41 μm/s) at 0 hour. After 2 hour incubation there were no significant differences in PM between all groups, while VCL in 50°C was significantly higher than 37°C and 70°C (40.88 ± 3.04 vs. 31.63 ± 2.80 and 38.20 ± 11.03 μm/s respectively). Average path velocity (VAP) in 50°C was significantly higher than other groups, 0 and 2 hours after thawing (p<0.05). Conclusion: It seems that thawing the buffalo semen in 50°C for 15 seconds could increase sperm kinetic parameters and it can improve subsequent fertility of buffalo spermatozoa.