Just Accepted

This article has been peer reviewed and accepted for publication. It is in production and has not been edited, so may differ from the final published form.

Effect of Cooling Rates and Equilibration Times on Post-Thaw Sperm Quality of Kail rams

Nasir Hameed , Muhammad Zubair , Nasim Ahmad, Aneela durrani, Muhammad Khan

Abstract

Context. The conflicting findings regarding the impact of equilibration time on post-thawed sperm quality underscore the need for further research to evaluate the impact of equilibration time and cooling rate on post-thaw sperm quality. Aims. The current study aimed to assess the combined impact of cooling rates and pre-freezing equilibration times on post-thaw sperm quality in Kail ram semen (n=5). Methods. Semen collection was performed using an artificial vagina at 42 °C. The pooled semen was divided into equal aliquots and subjected to either slow cooling (SC; -0.27 °C/min) or moderate cooling (MC; -0.36 °C/min) rates, transitioning from 37 °C to 4 °C. Equilibration times of 0, 4, 8, and 12 hours were employed before freezing. Key results. Semen samples undergoing the SC rate and equilibrated for 4 hours exhibited higher (P<0.05) percentages of progressive motile (PM), rapid progressive (RP), and medium progressive (MP) sperm compared to the MC rate. However, total motility remained unaffected by the cooling rate (P<0.05). Semen equilibrated for 4 hours demonstrated higher (P<0.05) percentages of PM and RP sperm, as well as improved kinematics (VCL, VAP, and VSL) compared to other equilibration times. Nevertheless, equilibration time had no (P>0.05) impact on ALH for semen samples subjected to the MC rate. Notably, the cooling rate did not affect post-thaw sperm kinematics, plasma membrane integrity, or live sperm percentage (P>0.05). Semen samples equilibrated for 4, 8, and 12 hours exhibited a higher (P<0.05) percentage of sperm with intact plasma membrane and viability compared to 0 hours. Conclusions. In conclusion, slow cooling and a 4-hour equilibration period proved optimal for preserving post-thaw sperm quality in Kail rams.

AN24013  Accepted 19 July 2024

© CSIRO 2024