EFFECTS OF LECITHIN, EGG-YOLK, FRUCTOSE AND PERIOD OF STORAGE AT 5 C ON BULL SPERMATOZOA DEEP-FROZEN TO -79 C

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Abstract
Bull spermatozoa were deep-frozen after periods of 0, 1 and 4 hr of equilibration at 5[degree]C prior to freezing. Their revival was scored by the motility score, the percentage motile and the percentage unstained by congo-red-nigrosin. By all scores the best results were seen after a 4-hr period and the highest numbers of motile spermatozoa were seen when 62 m[image] -fructose was mixed with the buffered sodium citrate diluent. There were higher survival rates in diluents containing 1% (w/v) egg lecithin than in those with 25% (v/v) egg yolk, and best counts of unstained spermatozoa were found in lecithin-containing diluents after 4 hr storage at 5[degree]C. In a second experiment, after replacement of part of the citrate buffer by 62, 123 or 185 m[image]-fructose solution, there was no significant change in the activity of the thawed spermatozoa, but the percentage of un-stained spermatozoa was significantly lower in diluents containing 185 m[image]-fructose than in those with 62 m[image]. One per cent lecithin gave better motility results than 0.5 or 2.0% and the proportion of unstained spermatozoa was higher in 2.0% than in 0.5% lecithin. Improvement in the percentage of unstained spermatozoa continued for up to 12 hr storage at 5[degree]C and best results were scored from semen diluted and equilibrated for 12 hr in a mixture of 62 m[image]-fructose, 60 m[image]-sodium citrate, 20 m[image]-phosphate buffer and 2.0 [image]-glycerol.