[Studies on the effect of phosphoric phenyl ester diamide as inhibitor of the rumen urease of dairy cows. 2. The metabolism of 15N-urea].
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.
D000821:Animal Feed; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D003612:Dairying; D006801:Humans; D010755:Organophosphates / Q000494:pharmacology*; D009943:Organophosphorus Compounds / Q000494:pharmacology*; D012417:Rumen / Q000187:drug effects / Q000201:enzymology*; D014508:Urea / Q000378:metabolism*; D014510:Urease / Q000037:antagonists & inhibitors
D010755:Organophosphates; D009943:Organophosphorus Compounds; C032022:phosphoric phenyl ester diamide; D014508:Urea; D014510:Urease
Untersuchungen zur Wirkung von Phosphorsäurephenylester-diamid als Inhibitor der Pansenurease bei der Milchkuh. 2. Mitteilung: Der Umsatz von 15N-Harmstoff.