Sperm-bound amidase activity as a marker for acrosomal integrity in bull spermatozoa

An assay for sperm-bound amidase activity was validated using bovine spermatozoa and N-benzoyl-DL-arginine p-nitroanilide as substrate. The assay had intra- and interassay coefficients of variations of 5 and 12%, respectively. It is an inexpensive, simple and rapid assay since 100 samples can be evaluated in 2 hours and it requires only 4 X 10(6) spermatozoa per sample. Sperm-bound amidase activity was proportional (r = 0.95) to the percentage of spermatozoa with an intact acrosome, as determined by differential interference-contrast microscopy. A change of five percentage units in the incidence of damaged spermatozoa was detectable. Using this procedure, assessment of sperm-bound amidase activity is therefore a sensitive and efficient means of evaluating acrosomal integrity.