Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.3.4.6 (urease)
 7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In two experiments with one dairy cow each the utilisation of urea-N after its ruminal or duodenal infusion was comparatively investigated on two crude protein levels and different urease activities in the rumen. The rations contained 9.6 (I) and 14.3 (II) g crude plant protein/100 g dry matter. After completed adaptation 50 g urea were daily infused in the rumen (R, via cannula) in 3 h resp. the duodemun (D, distal cannula of the reentrance cannula) in 6 h with the morning and evening feeding. In experiment II the urease blocker phosphoric acid phenylester diamide (D/PPD) was applied in an additional experiment synchronously with the duodenal urea application. On the first measuring day in each case the urea in the morning feeding was labelled with 17.4 atom-% 15N-excess (15N'). Measuring results in the sequence I R, I D, II R, II D, II D/PPD: 15N'-passage rate at the duodenum within 72 h in the TCA-soluble N-fraction 29, 18, 24, 13 and 16, in the TCA-precipitable N-fraction 59, 25, 41, 11 and 5% of the application, 15N'-excretion within 96 h in milk protein 6.8, 4.2, 4.6, 3.4 and 1.9, in faeces 20, 12, 19, 8 and 4, in urine 20, 32, 34, 56 and 75% of the application, 15N-balance 59, 56, 47, 36 and 21% of the application, passage rate of non-NH3-N in the duodenum 131, 118, 96, 107 and 99% of the total N-intake. After ruminal infusion there always was a higher NH3-concentration in the rumen and 15N-frequencies in the rumen proteins. One can conclude that urea-N that gets into the intestines is to a low degree used for duodenal protein supply as directly utilisable urea-N from the ration in the rumen. The difference increases with the protein content of the ration and the inhibition of rumen urease. The urea N-balance is to a considerably smaller degree influenced by the place of urea infusion particularly at a low level of N-supply, which is due to a better utilisation of the urea-N transported with intermediary metabolism from the intestines. The role of urease as a regulator of urea transport through the rumen wall cannot be corroborated.
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PMID:[Transport of urea nitrogen from the intestines into the stomach in dairy cows]. 652 64

Two lactating dairy cows supplied with rumen and duodenal re-entrance cannulae received with their rations containing 8.2% vegetable crude protein 180 g urea per day (I) or urea treated with the urease inhibitor phosphoric phenyl ester diamide (PPD, 1% of the N-quota). The cows, accustomed to urea, received the PPD-urea without adaptation (II) and after a 30-day adaptation (III) to PPD. On the first day of the experiment one half of the urea was given ruminally in its 15N-labelled form. 2 h after the isotope supplementation 62.5 and 24 mg NH3 and 6.58 and 21 mg urea/100 ml could be detected in the rumen juice of I to III. Within 72 h 16.6, 26.1 and 25.2% of the 15N-excess given (15N') passed the duodenum in TCA - soluble form and 31.2, 28.4 and 41.7% in TCA - precipitable form. 15.6, 24.4 and 21.5% of the total amount of 15N were excreted in urine and 4.5, 4.6 and 6.0% in the milk protein. The values for faeces were 14.4, 14,4 and 15.4%. The conclusion from these results and from the dynamics of the relative 15N' in the fractions of the rumen fluid is that with a limited inhibition of rumen urease by PPD as it develops after the adaptation, the utilisation of urea-N can be improved.
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PMID:[Studies on the effect of phosphoric phenyl ester diamide as inhibitor of the rumen urease of dairy cows. 2. The metabolism of 15N-urea]. 728 29