The Influence of Urea Ingestion on the Nitrogen Balance and Energy Metabolism of Rats

Abstract

Urea fed to rats as a supplement to a mixed maintenance ration, in quantities of 2 gm. per day, was almost entirely recovered as such in the urine and feces, as indicated by the balances of nitrogen, carbon and energy and by the ratios of carbon to nitrogen and energy to nitrogen in the urine. Of the total nitrogen ingested as urea 95.5% was recovered in the urine and 0.7% in the feces. Of the carbon and energy of the urea fed 98.5% and 99.8%, respectively, were found in the urine. The feeding of urea showed no significant effects on either the heat production or the respiratory quotients. The data lead to the conclusions that rats do not utilize urea to any significant extent, and that the excretion of urea does not exert a specific dynamic effect.