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

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Abstract
Laboratory and field expts. showed that heating of homogenized milk and pasteurized skim milk to 95[degree]C brought about chemical and/or physical changes so that spermatozoa with the milk diluted maintained motility approx. equal to that with egg yolk-citrate dilutes 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, opt. livability was obtained when the milk was heated to 95[degree]C for 1-10 minutes. Gentle boiling gave 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 for as long as one hour in a covered double boiler was not harmful to livability. Reaching the proper temp. (92 [degree]C minimum) appeared to be more important than length of the heating period. By use of the split sample technique, 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 5001 first service cows, the 60- to 90-day non-returns averaged 72.7% for the boiled, homogenized milk diluter and 71.4% for the egg yolk-citrate-penicillin-streptomycin diluter. Boiled homogenized milk and boiled pasteurized skim milk provide economical, easily prepared, practical diluting media for bovine semen.