EFFECT OF CRYOPROTECTANTS ON RELEASE OF VARIOUS ENZYMES FROM BUCK SPERMATOZOA DURING FREEZING

Semen samples from 12 bucks were extended with 10 different extenders containing glycerol, DMSO, glycerol + DMSO, and glycerol + lactose in varying concentrations as cryoprotective agents. The activities of acr osin, hyaluronidase, alkaline phosphatase (AKP), aspartate aminotransf erase (AST), alanine amino transferase (ALT) and lactic dehydrogenase (LDH) were assayed in equilibrated (Prefreeze) and frozen-thawed (Post freeze) semen samples. Significantly (P < 0.01) higher intracellular a ctivity of acrosin was recorded in semen samples extended with lactose than with the other extenders, with the maximum being with Tris yolk glycerol lactose (TYGL(180)). Effects of extenders on acrosin activity were significant (P < 0.01) at both of the pre-and postfreeze stages. However, extracellular activities of hyaluronidase, alkaline phosphat ase, transaminases (AST and ALT), and lactic dehydrogenase were signif icantly higher in extenders containing DMSO then lactose. Leakage of t hese enzymes was found to increase from the prefreeze to the postfreez e stage.