Freezing Ram Spermatozoa by the Pellet Method. II. the Effects of Method of Dilution Rate, Glycerol Concentration, and Duration of Storage at 5'c Prior to Freezing on Survival of Spermatozoa

Abstract

Five factorial experiments were conducted to examine the relationship between the effects of diluent composition, method of dilution, dilution rate, glycerol con-centration, duration of storage at 5°C prior to freezing, and dilution rate at thawing on the survival of ram spermatozoa after freezing by the pellet method. The optimal method of dilution, glycerol concentration, and duration of storage were found to vary according to the composition of the diluent. With moderately hypertonic (6. = O· 7-0'9 degC) raffinose-yolk-citrate diluents, best post-thawing survival of spermatozoa was achieved by dilution with the glycerol-containing diluent at 30°C prior to cooling, with 3-4% glycerol in the diluted semen, and by a short (1 hr) period of storage at 5°C prior to pellet freezing.