Effect of different thawing procedures on motility and kinetic parameters of frozen-thawed bull sperm

This study aimed to evaluate the effect of thawing temperature for deep-frozen semen by analyzing sperm motility and kinetic parameters. Before computer-assisted semen analysis (CASA), semen straws (0.25 mL) were thawed in a water bath using three protocols: 38 °C for 20 seconds (Group A, n = 6), 55 °C for 10 seconds (Group B, n = 6), and 65 °C for 5 seconds (Group C, n = 6). While total and progressive sperm motility showed a tendency to increase with higher thawing temperatures and shorter periods (65 °C for 5 seconds, Group C) compared to Groups A and B, these differences did not reach statistical significance (P > 0.05). Notably, the percentage of locally motile spermatozoa was significantly higher when semen was thawed at 65 °C compared to 55 °C (P < 0.05). Similarly, kinetic parameters were generally higher in Group C, with a statistically significant increase in DAP compared to Group B (P < 0.05). Conversely, LIN values were lower in Groups B and C than in Group A, reaching statistical significance (P < 0.05). The cytomorphological evaluation revealed no significant differences between the three groups in terms of the percentage of pathologically altered spermatozoa, live spermatozoa, or the prevalence of head, midpiece, or tail defects (P > 0.05). These results suggest that rapid semen thawing at 65 °C for 5 seconds may optimize sperm motility and kinetic parameters. However, further research with larger sample sizes is needed to evaluate the fertilization capacity of semen during artificial insemination.