FACTORS AFFECTING THE FERTILITY AND OTHER CHARACTERISTICS OF DEEP-FROZEN BULL SEMEN

Abstract

SUMMARY The fertility of twelve types of deep-frozen bull semen was investigated in a factorial test involving 1469 first-service cows. Factors examined were dilution rate (30, 20 and 13·3 million spermatozoa/ml., using 1 ml. per insemination), sugar in the diluent (fructose or arabinose) and equilibration time (1 hr or 18 hr). Only the last-named had a significant effect on fertility, 1 hr of equilibration yielding semen of somewhat lower fertility than 18 hr (58·4 v. 65·3% of non-returns to service at 3 months). The seminal motility and revival rate were also studied in stored samples. Motility was affected by the sugar used and by dilution, but not by equilibration time. The revival rate was affected only by equilibration time, but all such effects were small.