Changes in Motility Characteristics of Goat Spermatozoa During Glycerol-Equilibration and the Relevance to Cryopreservation

Abstract

Artificial Insemination (AI) with frozen Boer goat semen could be a viable option for genetic upgradation of non-descript local goats. To maximize the utilization of Boer germplasm, minimizing the losses due to poor freezability and improving the quality of frozen semen are the areas to be addressed. A study was conducted to assess the deterioration in the quality of semen in terms of motility characteristics of spermatozoa during the processing of semen for cryopreservation using Computer Assisted Semen Analysis (CASA) technique. A highly significant decline in sperm motility, progressive motility, path velocity and progressive velocity was noticed during equilibration. Semen samples with acceptable freezability differed from samples not freezing well by not showing any significant decrease in velocity characteristics of the spermatozoa during glycerol­ equilibration. The decline was significant in semen samples that froze poorly. Comparing the motility characteristics of spermatozoa during glycerol-equilibration in the good and poor samples, the progressive velocity in poor samples was significantly lower than that of good samples at 3 and 4 h of equilibration. The curvilinear velocity of spermatozoa was also significantly less in poor samples than good samples after 4 h. These results indicate that veloci ty of sperm motion plays a vital role in determining the post-thaw quality of frozen semen. Cryopreservation significantly affected the quality of frozen semen by lowering all the motion characteristics post-thawing. This study also revealed that the duration of exposure of spermatozoa to the cryoprotectant during equilibration is critical in cryopreservation of Boer cross goat semen. A shorter duration of2 h of equilibration with glycerol at SoC may be beneficial for Boer goat semen cryopreservation.