[Amide nitrogen in blood plasma of sheep]

The physiological concentrations of amide nitrogen in blood plasma of sheep taken before feeding, 60, 180, and 360 min, after feeding were determined. The concentration of the total amide nitrogen in plasma at intake of 7.6 g of nitrogen per day (45.55 +/- 3.85 mmol.1-1) was significantly higher (P less than 0.001) than at intake of 24 g of nitrogen per day (42.34 +/- 4.07 mmol.1-1). Between the concentrations of amide nitrogen unbound to plasma proteins (1.5 +/- 1.36 mmol.1-1) no significant differences in dependence on the nitrogen intake were found. The results prove that a substantial part of amide nitrogen in plasma is bound to proteins and that its level is relatively stable. A significant change was observed only in the concentration of the total amide nitrogen after a long-term feeding of sheep with some other diet. When the concentration of the total amide nitrogen in plasma was lower in relation to nitrogen intake, the urea concentration was higher.