Estimation of Nitrogen Digestibility in Poultry: Content and Distribution of Major Urinary Nitrogen Compounds in Excreta

The investigation concerned the digestibility of nitrogen and the content of uric acid, ammonia, and urea in urine and feces in White Leghorn layers. Eight colostomized hens were given a commercial cage-layer diet. Feces and urine were collected under acid conditions. Acidified urine contained more ammonia than untreated urine. For quantitative determination of ammonia, Urine collection ought to be done under acid conditions. Of urinary nitrogen uric acid represented 88%, ammonia 7%, urea 3%, and 2% unidentified. Urinary ammonia constituted 90% of ammonia in total excreta and urinary urea 86% of the urea in excreta. By means of these distribution factors and content of nitrogen compounds in total excreta, good estimates of the nitrogen digestibility were obtained. Our method appears to be applicable to chickens of other ages, sex, breeds, and environmental conditions.