Rumen Bacterial Urease Requirement for Nickel

Abstract

Lambs were fed a basal purified diet low in N (60 ppb) or the basal diet supplemented with 5 ppm of N to determine if rumen bacterial urease was a N-requiring enzyme. Two collection periods with lambs fed a diet in which all the N was supplied as preformed protein (casein) indicated that ruminal urease activity was much lower in lambs fed the low N diet. When 1% urea was added to the basal diet, urease activity increased slightly with both treatments, but bacterial urease activity was still much higher in the lambs receiving 5 ppm of N. Ruminal volatile fatty acids were not influenced by dietary N. Ruminal urease requires N for maximal activity.