Pyridine Nucleosidase in Bull Semen I. Breed and Sire Differences in Enzyme Concentration

Abstract

The concentration of a pyridine nucleosidase which cleaves the nicotinamide-ribose bond in NAD and related compounds was assayed using the cyanide addition reaction in semen samples collected by artificial vagina from 246 bulls. Among the 205 sires of recognized dairy breeds the nucleosidase concentration ranged from 0 to 1470 units/ml semen. Of the dairy sires 18 % produced semen containing no nucleosidase activity. Among the 41 sires of recognized beef breeds 54 % had no nucleosidase and the highest concentration was 630 units/ml semen.