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<p><span lang="EN-US">Levels of supplementation for grazing dairy cows have been studied with the objective to determine the best relationship between amount of supplements and milk production. In this study twenty-four Gir x Holstein crossbred cows were evaluated in irrigated and fertilized Panicum maximum Jacq. cv. Tanzânia pasture, in a rotational grazing system with seven UA/ha. Cows were distributed in randomized blocks, according to the days of lactation, milk production and parity of lactation, with twelve replicates. The experiment occurred from March to October 2010, the experimental treatments were 2.5 and 5.0 kg/animal/day of concentrate supply. All animals also received 20 kg/animal/day of corn silage during season. At the end of each grazing cycle (24 days) animals were weighed and had their body condition evaluated. Milk production (MP), milk yield corrected for 3.5% of fat, protein (CP), fat (F), lactose (L), total solids (TS), nonfat dry extract, milk urea nitrogen (MUN) and somatic cell count were determined. MP in kg/day and milk adjusted to 3.5% of fat, F, CP, L, TS levels and solids, in kg and MUN (mg/dL) differed between the treatments and were higher for cows fed 5.0 kg in comparison to those received 2.5 kg of concentrate/animal/day. Production and composition of milk was greater when supplemented cows on fertilized and irrigated pasture received 5.0 kg of concentrate/day.</span></p>