The objective ofthis study was to evaluate the effect of different true protein:non-proteinnitrogen ratios in supplements on intake and ruminal transit and degradationdynamics of neutral detergent fiber (NDF) in grazing cattle during rainy season.Five crossbred Holstein × Zebu steers, averaging 335±35 kg of bodyweight and fitted with rumen and abomasum canullaes were used. The treatmentswere: control (only pasture), and supplements based on urea, 2/3 of nitrogenouscompounds from urea and 1/3 of nitrogenous compounds from albumin, 1/3 of nitrogenouscompounds from urea and 2/3 of nitrogenous compounds from albumin, and albumin.Two hundred grams/d of crude protein (CP) were supplied from supplements. Theexperiment was carried out according to a 5 × 5 Latin square design, withfive 15-day experimental periods. There were no effects of supplementation onvoluntary intake, except for CP intake, which was increased by supplementation.The replacement of urea by albumin in the supplements caused linear effect onthe CP intake. The intakes of the other diet components were not affected bythe supplement composition. There was no effect on ruminal rate of passage offibrous compounds. Supplementation increased the estimates of common rate oflag and degradation of NDF. However, no effect of supplement composition alterationwas observed on this parameter. Supplementation of cattle with rumen degradable(protein or non-protein) nitrogenous compounds for grazing cattle during rainyseason does not affect voluntary intake of pasture.
