Preliminary Fertility Results with Frozen Bovine Spermatozoa

Abstract

The fertility of bovine spermatozoa frozen in a concentrated form (200 × 106 motile spermatozoa per milliliter of extender), thawed at 5° C. at the bull stud, further extended to approximately 10 × 106 motile spermatozoa per milliliter and used for breeding 24 to 60 hours later, was compared with that of semen frozen in single-breeding vials. The latter were thawed at the farm just prior to insemination. The split sample technique was used with two ejaculates from three different bulls. Prefreezing processing and freezing procedures were slightly modified from those reported by Polge et al. and Dunn et al. Unfrozen semen processed in the conventional manner was used for the control breedings. All semen was extended to provide 8 to 10 million motile spermatozoa per insemination, though estimates made later indicated that actual numbers varied between 4 and 14 million. The 60- to 90-day nonreturns to first services were as follows: unfrozen control, 459 services, 74.5%; frozen “concentrated,” 449 services, 51.7%; frozen as single breeding samples and stored one day at −79° C., 55 services, 72.7%; frozen as single breeding samples and stored 103 days at −79° C., 92 services, 77.0%. © 1955, American Dairy Science Association. All rights reserved.