Nitrogen excretion in Japanese quail during protein depletion and repletion.

The influence of protein depletion and repletion on the excretion of uric acid, urea, creatinine and free arginine as well as on the activities of xanthine dehydrogenase and arginase in Japanese quail was studied. Adult cockerels normally fed until the age of 42 days were kept on a protein free diet for 21 days and subsequently for 14 days on the previous normal diet. The control group was fed normal diet for the whole time. In 1-5 days intervals the enzyme activities and the N-metabolites in 24 hours excreta were determined. Protein free diet feeding evoked rapid (in term of 8-9 days) diminution of the excretion of N-metabolites, as well as of the xanthine dehydrogenase activity up to the fourth-tenth part of the initial values. The arginase activity was not influenced by this treatment. Body mass decreased by 36%. Returning to the normal protein feeding reverse the values of observed parameters to their initial levels within 8-9 days. It was concluded that changes in excreted N-metabolites caused by protein free feeding were rapid and recoverable by returning to normal diet.