Abstract
Four treatment methods for the preparation of deep-frozen bull semen were tested for fertility in a factorial design involving the artificial insemination of 1728 first-service cows with the following results 30 min equilibration, no fructose in the diluent, [image] of non-returns to service at 3 months, with equal treatment groups of 432 cows. The improvement in fertility after equilibration in the presence of fructose was highly significant (P<0.01), but not in its absence, when fertility was depressed even in equilibrated semen. There was a higher revival rate of spermatozoa after the longer period of equilibration and the use of fructose in the diluent significantly improved the percentage of motile spermatozoa after thawing.