Raçôes com diferentes níveis de fibra em detergente neutro na alimentaçâo de bovídeos em confinamento

A 4 x 4 latin square digestion trial was conducted with 12 noncastrated growing male cattle consisting of four Nelore (NEL), four Holsteins (HOL) and four Mediterranean buffalo (BUF), average weight 277, 299, and 328 kg, respectively, to determine the maximum, optimum, and adequate levels of neutral detergent fiber (NDF) in rations with different levels of NDF. Each genetic group (NEL, HOL, and BUF) represented a 4 x 4 Latin square with four levels of NDF in the ration and four 28-day periods. Rations were formulated to meet NRC (1984) requirements with decreasing levels of NDF (76.0, 66.5, 58.7, e 51.9 percent) for rations A, B, C, and D rations, respectively. Dry matter (DM) and digestible dry matter (DDM) intakes expressed as g/kg(0.75) or as percent live weight (LW), increased linearly as the NDF level of the ration decreased. The NDF and digestible NDF intakes by the animals were constant for all rations. No differences were detected among genetic groups. The average NDF intake was 57.1 g/kg(0.75) and 1.3 percent LW, respectively. Digestible energy and digestible organic matter energy (DOM) increased linearly as the NDF of ration decreased. The NDF levels used in the ration were adequate to determine the maximum NDF intake (1.3 percent LW), but were not adequate to determine the optimum intake of NDF by the animals or the level of NDF adequate in the ration for cattle in confinement eng