The Relationship of Egg Yolk and Glycerol Content of Diluters and Glycerol Equilibration Time to Survival of Bull Spermatozoa after Low Temperature Freezing

Abstract

Summary In a factorial design experiment with three levels of egg yolk (18.4, 23.0, and 27.6%), three levels of glycerol (6, 8, and 10%), and four glycerol equilibration times (2, 6, 12, and 18 hours) there was a progressive increase in sperm survival in all diluter treatments after freezing to −75° C. as the glycerol equilibration time was increased from 2 to 18 hours. A significant interaction between egg yolk and glycerol levels also was demonstrated. There were no significant interactions involving glycerol equilibration time and the other variables. In a second factorial design experiment, four egg yolk levels (15, 20, 25, and 30%), five glycerol levels (5, 6, 7, 8, and 9%), and three storage times at 5° C. (0, 1, and 3 days) after thawing were used. A highly significant interaction of egg yolk and glycerol levels was again demonstrated. As the egg yolk level was increased, the glycerol level had to be increased also for optimal sperm survival after freezing. A diluter containing 20% egg yolk and 7% glycerol gave best sperm survival after freezing.