Effects of decreasing roughage NDF in diets with high inclusion of DDGS on performance, feeding behavior, and ruminal parameters in Nellore bulls

•Decreasing levels of rNDF up to 7 % in diets with high inclusion of corn DDGS improved dry matter intake and ADG.•Decreasing levels of rNDF down to 4 % did not cause acidosis in diets with high inclusion of DDGS.•Decreasing levels of rNDF changed the consumption pattern of the diet in favor of longer particles. This study evaluated decreasing levels of roughage NDF (10, 7, and 4 % in DM) in DDGS-based finishing diets. In experiment 1, growth performance, feeding behavior, and carcass characteristics were evaluated on 18 Nellore bulls blocked by initial body weight (BW), with 6 replicates per treatment, in a complete randomized block design. In experiment 2, digestibility, feeding behavior, and ruminal fermentation were evaluated on 6 Zebu crossbred steers in two, 3 × 3 Latin square designs. Differences were considered significant at P < 0.05 and trends were declared at P < 0.10. In experiment 1, DMI increased quadratically with decreasing roughage NDF (rNDF) with the greatest DMI value achieved at 7.43 % rNDF (P