The objetives of this research were to detecthow many days were necessary to animals adapt to the diets, by measuring intake;to evaluate the effect of crescent levels of wheat middlings as a replacementfor corn meal in the diets on the milk production and composition, the intakeand apparent digestibilities of dry matter (DM), organic matter (OM), neutraldetergent fiber (NDF), ether extract (EE), total carbohydrates (TC), crude protein(CP), intake of total digestible nutrient (TDN) and non fiber carbohydrate (NFC),as well as diets economical evaluation. Twelve Holstein cows were allotted tofour balanced 4 x 4 Latin square design in accordance with the lactation period.The four experimental diets were formulated to contain 70% corn silage and 30%of concentrate. Crescent levels of wheat middlings were used in the concentrate(0, 33, 67 e 100%) as a replacement for corn meal, for the treatment 1, 2, 3and 4, respectively. All diets were isoproteics, with aproximately 15% CP. Fivedays was enough for adaptation of the animals to the rations. There was linearincrease in the intake of NDF, expressed as kg/day and %LW and linear decreasein the intake of NFC, however there was no change in the intake of DM, OM, CP,EE, TC and TDN. The total apparent digestibilities of DM, OM, TC and CP presenteda linear decrease response, with increasing levels of wheat middlings in thediets. However, the total apparent digestibilities of EE and NDF did not change.The milk production corrected or not for 3.5% fat and milk protein, fat, milkdry matter and deffated milk contents were not influenced by the wheat middlingslevels in diets.
