ABSTRACT - This work was conducted to evaluate the effects of different concentrate levels on the voluntary intake and the apparent total and partial digestibilities of dry matter (DM), organic matter (OM), ether extract (EE), neutral detergent fiber (NDF) and total carbohydrates (TCH), in the rumen and in the intestines. Five rumen and abomasum fistulated Holstein calves, with initial average age of 5.8±0.7 months and initial average of 107.4±11.0 kg LW were allotted to a 5x5 Latin square design (treatment x period). The animals were housed in individual stalls and full fed diets (DM basis) containing 30.0, 45.0, 60.0, 75,0 and 90.0% of concentrate. The diets were based on coast-cross grass hay as forage and soybean meal and ground corn grain in the concentrate. The chromic oxide was used as marker to estimate the fecal and abomasal DM flows. The intakes of DM, OM, CP and TCH, in kg/day, were not affected by diets, while that of EE intake increased and NDF intake linearly decreased, when expressed in %LW and g/kg.75 as the dietary concentrate levels increased. Total apparent digestibilities of DM, OM, EE and TCH linearly increased as the dietary concentrate levels increased, but NDF digestibility was not affected. Ruminal digestibilities of DM, NDF and TCH did not vary as the dietary concentrate levels increased, but the OM digestibility increased and that of EE linearly decreased as the dietary concentrate levels increased. The intestinal digestibility of DM did not vary, but that of OM and TCH linearly increased. The EE and NDF digestibilities were not affected by the inclusion of crescent concentrate levels in the diets.
Holstein calves; concentrate; intake; digestibility
