Effect of Glycerol Equilibration Time, Glycerol Level, and Rate of Temperature Descent on the Freezing of Ram Spermatozoa2

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Abstract
Using an egg-yolk-citrate extender, a study was made to determine the effects of different glycerol levels, equilibration times, and rates of freezing on the freezing, storage, and subsequent recovery of ram semen. Analysis of variance of these data indicated that ram spermatozoa frozen and stored at −79° C. had the highest percent recovery when 3.5, 5.25 and 7% glycerol levels were used. Concentrations of 14% glycerol greatly decreased survival after freezing. Under the conditions of this experiment, a 0.5-hour equilibration time was superior to an 18-hour equilibration period. There was no statistical significance between two rates of freezing; however, the semen frozen 2° C. per minute from 4° C. to −20° C, 4° C. per minute from −20° C. to −50° C. and 10° C. per minute from −50° C. to −79° C. had a higher percent recovery as compared to semen frozen more rapidly. There was a significant decline in percent recovery between 48 hours and 10 days storage. Copyright © . .