The nutritional value of typical feeds (n = 6) for ruminants was evaluated with chemical analysis and procedures for determination of individual nitrogen fractions by Cornell system. Three samples of roughages and three samples of concentrates were dried, milled, analysed for individual nutrients and then analysed for individual nitrogen fraction. Nitrogen fractions A, B1, B3, B3 and C were from 12.5 to 25.9 % of crude protein (CP), 5.0 to 32.8 % of CP, 3.9 to 60.8 % of CP, 4.3 to 39.5 % of CP and 4.1 to 11.2 % of CP, respectively. The knowledge of the protein degradability of feed rations is important for understanding the ruminants’ digestibility processes.