Diluters for Bovine Semen. I. Fertility and Motility of Bovine Spermatozoa in Boiled Milk

Abstract

Summary Laboratory and field experiments were conducted to study the use of milk as a diluter for bovine spermatozoa. The heating of homogenized milk and pasteurized skimmilk to 95°C. brought about chemical and/or physical changes so that spermatozoa diluted with the milk were capable of maintaining motility approximately equal to their motility when diluted with egg yolk-citrate during a storage period of 16 days. Motility survival was very poor in unboiled milks, seldom exceeding two days, even though the milks had been pasteurized. In general, optimum spermatozoan livability was obtained when the milk was heated to 95°C. for 1 to 10 minutes. Gentle boiling yielded better motility survival results than did vigorous boiling. Boiling milk in an open vessel for more than 10 minutes reduced the duration of motility, but heating as long as one hour in a covered double boiler was not harmful to livability. Reaching the proper temperature (92°C. minimum) appeared to be a more critical consideration in obtaining maximum spermatozoan livability than the length of the heating period. By use of the split sample technique, the fertility of bovine semen diluted in boiled homogenized milk containing no antibiotic was compared with semen diluted in egg yolk-citrate (1:1) containing penicillin and streptomycin. On the basis of inseminations to 5,001 first service cows, the 60- to 90-day nonreturns averaged 72.7 per cent for the boiled homogenized milk diluter and 71.4 per cent for the egg yolk-citrate-penicillin-streptomycin diluter. Based upon satisfactory spermatozoan livability and fertility, it is concluded that boiled homogenized milk and boiled pasteurized skimmilk provide economical, easily prepared, practical diluters for bovine semen.