With the objective of evaluating the ruminal degradation of the dry matter and the crude protein of different concentrated feed used when feeding bovine, through the in situ technique, we used three young Nelore steers, rumen fistulated, with 24 months old, and weighting approximately 350 kg. The feed samples were weighted and put inside of nylon bags (6,5 x 4,0 cm of free area) with 50 micras porosity in the quantity of 1,0 g of dry matter, and they were put in decreasing order in the rumen with intervals of 48, 36, 24, 12, 6, 3 and 0 hours. Six feeds were analysed: corn gluten, citrus pulp, soybean meal, wheat meal, ground corn and peanut meal. The data were adjusted by non linear regression, according to the model p = a + b(1-e-ct). The effective degradability of the dry matter were, in order, 29, 3, 76, 6, 71, 3, 60, 4, 59, 6 and 60,8, to the passage ratio of 5% an hour, and of the crude protein, 8,5; 56,1; 57,4; 67,9; 30,1; and 85,2 fot the same passage ratio. The citrus pulp presented high value for the effective degradability of DM (76,6%), the corn a slow degradation ruminal of PB, with the value of the degradation ratio for the fraction “b” of 2,9%, the corn gluten presented a fraction "a", of 11,9% for to DM; where a source of protein of high ruminal escape, it presented ED of 8,5%; the peanut meal presented value, for the fraction "b", of 67,3%, the nutritional value of this food is similar to the soy meal, but had the largest ED of CP 48% highest than the soy meal. The corn gluten presented low ruminal degradation, while the citrus pulp and the corn had slow ruminal degradation, specially when compared to the peanut meal.
concentraded feeds; ruminal degradation; nylon bags; “in situ” technique