Freezing Bovine Semen. I. Techniques for Freezing Bovine Spermatozoa in Milk Diluents

Effects of level of glycerol and method of adding it, equilibration time, and addition of sugars to milk diluents, on the survival of spermatozoa after freezing, were studied. Heated and cysteine-treated homogenized milk and skimmilk diluents gave survival rates after freezing equal to those obtained with egg yolk-citrate diluent. Spermatozoa frozen in milk diluents maintained higher motility after thawing and storage at -F 5 C. than those frozen in egg yolk-citrate. In skimmilk diluent, prefreezing glycerol equilibration periods of 30 rain. and 4 hr. resulted in spermatozoan survival equal to or better than 18 hr. Adding 1.25% fructose to a skimmilk diluent resulted in a significant increase in freezabitity of bull spermatozoa as compared to untreated controls. Editor.