Preservation of Bovine Spermatozoa by Freezing in Straws: A Review

Abstract

Plastic straws for packaging bovine semen have been advocated by a growing segment of the artificial insemination industry, particularly in Europe and more recently in the United States. Following an extensive review of the literature, we formed the following conclusions: Conception rates with semen frozen in straws are comparable to fertility of semen frozen in ampules, and prospects are encouraging for further improvements with the straw as procedures are refined. Fertility of semen frozen in .25 ml straws is equal to or higher than fertility of semen frozen in larger straws, in the hands of “good” inseminators. Survival of spermatozoa frozen in straws is equal to or higher than survival after freezing in ampules. Spermatozoa frozen in straws are no more fertile than those frozen in ampules, and the number of live spermatozoa per insemination for optimal fertility appears similar for straws and ampules. The percentage of spermatozoa deposited in the cow is definitely in favor of straws sealed with nonabsorbable material. Greater utilization of storage equipment is possible with the straw. Straws should be thawed rapidly, but caution must be exercised to prevent excessive wanning and subsequent cold shock. Semen frozen in straws cannot compensate for improper semen handling and poor inseminating techniques. © 1974, American Dairy Science Association. All rights reserved.