SURVIVAL OF FROZEN BOVINE SPERMATOZOA FOLLOWING MINIMUM EXPOSURE TO GLYCEROL

Bull spermatozoa in several buffered egg yolk media and in skim milk were exposed at 5°C to varying levels of glycerol for 6 hrs, 30 min, and approximately 10 see prior to freezing. Freezing was done by placing droplets of the extended semen in small holes on blocks of Dry Ice. Highly significant improvement in sperm motility following freezing and thawing was obtained with the 10-sec exposure in comparison with the 30-min and 6-hr exposures, which did not differ from each other. Part of this difference can be attributed to the slightly harmful effect of glycerol on spermatozoa during the longer exposure periods at 5°C before freezing. However, the survival rate during freezing was improved by the 10-sec treatment, suggesting that the conditions provided by the brief exposure to glycerol more fully protected the spermatozoa than did prolonged exposure. Motility following freezing and thawing also was affected by the thawing medium, which indicates that this may be an important consideration in thawing material which is to be diluted at the time of thawing. © 1969.