Influence of Seminal Dilution Ratios and Level of Egg Yolk during Cooling and Freezing of Bovine Spermatozoa in Straws

Abstract

Semen from each of five bulls was used in an experiment of factorial design to determine the effect of initial seminal dilution ratios of 1:4, 1:2, 1:1, or 1:.5 (semen:extender) and levels of 4, 8, 12 or 16% egg yolk during cooling on spermatozoa frozen in straws. The 1:4 dilution ratio resulted in motility similar (P>.10) to that of spermatozoa diluted 1:2 or 1:1, but greater (P<.05) than when semen was diluted 1:.5. Post-thaw motility of spermatozoa cooled in the presence of 4% egg yolk was similar (P>.05) to that with 8% egg yolk, but greater (P<.05) than with 12 or 16% egg yolk. The influence of .5, 1, 2, 4, 8, 16 or 32% egg yolk during cooling was investigated in a second experiment of factorial design with semen from each of seven bulls. Post-thaw motility of spermatozoa cooled in .5, 1, 2, 4 or 16% egg yolk was similar (P>.10) but greater (P<.05) than for spermatozoa cooled in 8 or 32% yolk. In a third experiment, the influence of glycerolization by final dilution at ratios of 1:1, 2:1, 3:1 or 4:1 (extended semen:glycerol extender) with extender containing 14, 21, 28 or 35% glycerol, respectively, was studied using semen from each of seven bulls. Post-thaw motility did not differ due to glycerolization procedure (P>.25). In experiment 4, semen from each of six bulls was utilized to evaluate the influence of 1, 2, 4, 8, 16 or 32% egg yolk during freezing. Post-thaw motility was similar (P>.10) for spermatozoa frozen with 2, 4 or 8% egg yolk and greater (P<.01) than for spermatozoa in 1 or 32% egg yolk. Post-thaw motility of spermatozoa frozen with 16% egg yolk did not differ (P>.05) from that with 1, 2 or 4% egg yolk, but was lower (P<.05) and higher (P<.01) than that with 8 or 32% egg yolk, respectively. Copyright © 1977. American Society of Animal Science . Copyright 1977 by American Society of Animal Science.