Freezing Bovine Semen. IV. Effect of Freezing on the Metabolic Activity of Bovine Spermatozoa during and after Storage at −79° C,

Open Access
Publisher Website
Google Scholar
Abstract
No evidence of respiratory activity by bull spermatozoa diluted in skim milk-glycerol during storage for 6 months at -79[degree]C could be demonstrated as measured by production of Cl1402 from radioactive substrates present in the frozen medium. However, freezing resulted in harmful effects on post-thawing metabolism of spermatozoa. After 6 months at -79[degree]C, twice-washed spermatozoa showed 34% less C14O2 production from glucose -U-C14 during post-thawing incubation for 6 hours at 5[degree]C than during a similar pre-freezing incubation period. Unwashed sperm, frozen and stored for 1 hour, produced 61% less lactic acid during post-thawing incubation for 3 hours at 37[degree]C than sperm from the same semen samples which were not frozen. The 36% loss of motile sperm due to freezing was not sufficient to explain the greatly reduced lactic acid production. Sperm stored frozen for 1 hour in skim milk-glycerol showed significantly greater post-thawing lactic acid production during incubation under air than those frozen in 1:4 egg yolk-citrate-glycerol, even though fewer sperm survived freezing in skim milk. Adding 1.25% fructose to skim milk-glycerol and egg yolk-citrate-glycerol diluents resulted in greater lactic acid production by both frozen, thawed and unfrozen spermatozoa. However, frozen samples still showed greatly depressed metabolic activity as compared to unfrozen samples.