[Effect of different amounts of carbamide on nitrogen digestibility and metabolism in broilers. II]

Experiments were carried out with one-hundred broiler birds of one and the same age group, breed, and origin, divided into five groups in order to follow up the effect of various amounts of urea on their physiologic state. A balance experiment was conducted to establish the effect of urea on the digestibility of nutrient matter and the metabolism of nitrogen with the use of nine birds per group, divided into three subgroups. Urea was added to a protein-balanced diet from the 20th to the 60th day in the following amounts by groups: I--2 percent; II--4 per cent; III--5 per cent; and IV--6 per cent. It was also found that with the increase of urea in the ration at the rates indicated above there was a progressive rise of both the amount of urea and the nonprotein nitrogen in the blood as well as the amount of nitrogen excreted with the urine. The intake of such amounts of urea lowered the assimilation of nitrogen by 4 to 9 per cent as against its initial level in the ration, and by 7 to 11 per cent--as against the level of digested nitrogen.