01540naa a2200217 a 450000100080000000500110000800800410001910000190006024500870007926000090016652010020017565000120117765000090118965000110119865000110120965000110122065300110123165300110124270000200125377300490127317861061995-09-12 1943 bl --- 0-- u #d1 aPEARSON, R. M. aThe utilization of urea in the bovine rumen. 2. The conversion of urea to ammonia. c1943 a1. In the utilization of urea by dairy cattle the first stage is probably the conversion of urea to NH3 in the rumen.. Moreover, the urease activity of the rumen ingesta is so great at all times of the days, wheatever the time of feeding, and remains so little affected by relative- ly large amounts of urea, that all the urea likely to be fed, event to a high yielding cow in full lactation, would readily be converted to NH3 within 1 hr. This fact has been confirmed by Wegner, Booth, Bohstedt & Hart [1941], who found a marked increase in N.P.N. and NH3 in the rumen after a urea meal but were unablke to detect urea it self. 2. The urease of the rumen resembles, in activity, that from soya and jack beans. Chan- ges in its activity with changes in temperature and pH, and its behaviour in the presence of such inhibitors as quinone and NaF, are typical of enzymes of the urease type. Prelimi- nary attempts to obtain enzyme preparations free bacteria have, however, proved unsuc- cessfull. aammonia aurea aBovino aRúmen aUréia aAmonio aBovine1 aSMITH, J. A. B. tBiochemistry Journalgv.37, p.148-153, 1943.