Deep-freezing ram spermatozoa: the effects of milk, yolk-citrate and synthetic diluents containing sugar.

Abstract

In a factorial experiment skim milk, egg-yolk-citrate and synthetic diluents composed of fructose or lactose, sodium chloride and phosphate buffer containing 3\m=.\0%w/v of a lyophilized preparation of non-dialysable solids from (cow) milk were used as diluents for deepfreezing ram spermatozoa and for incubating spermatozoa at 37\s=deg\C after thawing. All samples of semen were diluted forty-fold before freezing. Egg-yolk-citrate was inferior to skim milk as a diluent for freezing spermatozoa and for incubating spermatozoa after thawing. Of the two synthetic diluents, lactose synthetic was better for freezing spermatozoa whilst fructose synthetic was better for incubating spermatozoa after thawing. Only spermatozoa frozen in the lactose synthetic diluent and resuspended after thawing in the fructose synthetic survived incubation at 37\s=deg\C for 2 hr as well as spermatozoa frozen and incubated in skim milk diluents. Two factorial experiments compared egg-yolk-citrate and skim milk as diluents for freezing semen diluted from tento forty-fold. At ten-fold dilution, revival was much the same after freezing in milk or egg-yolk-citrate. A twentyor forty-fold dilution was better than a tenfold dilution in milk, but revival was depressed at these higher dilution rates after freezing in egg-yolk-citrate. When semen was frozen at a ten-