THE RELATIONSHIP BETWEEN FERTILITY AND POST-FREEZE MOTILITY OF BULL SPERMATOZOA (BY PELLET FREEZING) WITHOUT GLYCEROL

Glycerol has been the most widely-used protective agent for the freezing of bull semen. However, Nagase, Graham & Niwa (1964) demonstrated that bovine spermatozoa could be frozen without the addition of glycerol. The purpose of this experiment was to determine whether a relationship exists between the motility of an individual bull's semen after subjecting it to the stress of freezing without the protection of added glycerol and the fertilizing capacity of that animal's semen after freezing by commercial means. Semen used in this study was obtained from adult bulls in regular use at a commercial bull stud. Motility, volume and sperm cell concentration were recorded and a 0\m=.\5ml sample was taken from the first ejaculate of each bull immediately after collection. The 0\m=.\5-mlsemen sample was diluted in 1\m=.\5ml of a solution containing 18\m=.\5g of raffinose/100 ml of water and 20 % egg yolk by volume. The sample was then cooled slowly from 37 ° C to 5 ° C and was frozen 4 hr after collection, on dry ice using the pellet freezing method develo-ped by Nagase & Niwa (1964). This method consisted of placing three drop