the objective of this study was to evaluate the levels of concentrate for growing calves. four holstein × brahman crossbred calves with average age of 7 months and 155 kg of body weight were used, distributed into one latin square design (4 × 4). the animals were fed ad libtum in the form of complete diet containing levels of 20, 40, 60 and 80% of concentrate on the dry matter basis (dm). the diets were composed of cynodon dactylon hay, corn, soybean meal and mineral mixture, and were isoprotein (15.4%). the dm, organic matter (om), neutral detergent fiber (ndf) and total carbohydrate (tc) consumption showed linear response; and crude protein (cp) and total digestible nutrients (tdn), quadratic response; expressed in kg/day. when expressed in %bw, the om, cp, ee and tdn consumption presented quadratic behavior; as dm, ndf and tc showed linear behavior. the apparent total digestibility dm and cp coefficients were quadratic influenced by the levels of concentrate, while om, ee, ndf and tc showed linear behavior. no effect was observed for the average concentration of ammoniac nitrogen, depending on the levels of concentrate, for each time of analysis. however, for ph, there was influence of the levels for the times analyzed. likewise, no effect was observed for the average concentration of serum glucose, however, for urea nitrogen serum (uns), a linear negative effect was observed, depending on the levels for each post-feeding time. therefore, up to 60% of concentrate could be included in the diet of calves; however higher levels can affect the use of bulky.