Osmotic Pressure and pH Effects on Survival of Frozen Bovine Spermatozoa

Abstract

Semen from ten hulls was extended in egg yolk extenders buffered with five concentrations of Tris adjusted to four pH levels, and containing two levels of glycerol, to study their interactions during semen freezing. Spermatozoa in these 40 media (5 4 2) were equilibrated for 1.5 and 6.0 hr, frozen at 0.8 and 3.0 C/minute in the critical range, and stored seven days at --196 C. Duplicate estimates of the percentage of motile spermatozoa made immediately after thawing (6,400 obsmwations) indicated that the freezing rate and equilibration time had little effect on survival. The percentages of motile spermatozoa for the 6.4 and 8.8% glycerol levels were 30 aud 28, for the 0.15, 0.20, 0.25, 0.30, and 0.35 5[ Tris-buffered yolk extenders 37, 40, 37, 28, and 5; and for the pH's of 6.0, 6.5, 7.0, and 7.5, 25, 29, 31, and 31, respectively. These effects were statistically significant (P < .005).