The Effect of Methods of Adding Egg Yolk and Monosaccharides on the Survival of Frozen Bull Spermatozoa

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Abstract
The inclusion of 25% egg yolk in both the nonglycerol and the glycerol fractions of extenders for frozen semen was compared with including 50% egg yolk in the nonglycerol fraction and none in the glycerol fraction. The final compositions of these 2 extenders were identical. The average percentages of motile sperm immediately after thawing were 30.5 and 22.3 for the 2 methods, respectively, and the average 60- 90-day nonreturn percentages for 1515 first services were 68.0 and 59.7 respectively. These differences were highly significant statistically (P< 0.01). Fructose, glucose, or xylose was added to give a final concentration of 1.0% by adding the sugar entirely in the nonglycerol fraction, equally in the nonglycerol and glycerol fractions, or entirely in the glycerol fraction. The 3 methods of incorporating the sugars resulted in 21.6, 28.4, and 28.4% motile sperm, respectively, immediately after thawing. Average percentages of motile sperm in the extenders containing the 3 sugars were fructose, 27.9; glucose, 26.4; and xylose, 24.2. In both cases differences were highly significant (P<0.01) when tested by means of the analysis of variance.