INFLUENCE OF GLYCEROL CONCENTRATION AND FREEZING TO −79 C ON OXYGEN UPTAKE AND LIVABILITY OF BOAR AND BULL SPERMATOZOA

Abstract

Boar and bull spermatozoa were diluted in a skim milk–egg yolk–glucose extender containing 0, 7.5, or 15% glycerol (v/v) and incubated aerobically for 6 hr at 37 C. Other partially diluted boar semen samples were cooled to 5 C. Glycerol was added to a final concentration of 0, 7.5, and 15%. Samples were frozen to −79 C, rewarmed, and incubated for 3 hr at 37 C. The presence of glycerol in the extender depressed (P < 0.01) the oxygen uptake by nonfrozen boar and bull spermatozoa during the 6-hr incubation period. The reduction of oxygen uptake by semen samples increased as the level of glycerol in the extender increased. There was a corresponding decrease (P < 0.01) in the number of motile cells at the conclusion of the incubation period. Glycerol appeared to have more of a detrimental effect on boar spermatozoan oxygen uptake. The rate of oxygen uptake by boar semen samples postfreezing was extremely depressed, suggesting that spermatozoa surviving the freezing process metabolize at a much lower rate than normal. Active progressive motility of most of the surviving boar spermatozoa ceased within 1–2 hr of incubation under the in vitro conditions of this experiment.