Factors Affecting the Maintenance of CO2 Levels and the Survival of Bovine Spermatozoa in Carbonated Diluents

Abstract

Summary Several studies have demonstrated the necessity of maintaining CO 2 levels and reducing oxygen in the sealed ampule for optimum sperm survival during storage in the carbonated Illini variable temperature (IVT) diluent. For improved survival, it was found that the head space in the sealed ampule should be as small or smaller than the fluid phase. The addition of catalase greatly improved sperm livability, particularly when the extended semen was sealed in ampules with a large head space, indicating that oxygen damage was occurring. Flushing the ampules with CO 2 immediately before filling resulted in better sperm survival when no catalase was used during storage at 26.5C. A glucose oxidase-catalase preparation added to the diluent supported sperm livability as well at 5C, but was poorer at 26.5C than the diluent containing crystalline catalase. Extended semen survived much better at room temperature (22–27C) when stored in sealed glass ampules than when stored in porous plastic bulbs. The importance of controlled CO 2 levels was also demonstrated by extending semen with IVT diluents in which the CO 2 was generated by the reaction of citric acid with sodium bicarbonate. Sperm survival was best in the diluent containing the most CO 2 and was progressively poorer as the amounts of CO 2 were decreased when stored at 5 and 26.5C.