The experiment was carried out to evaluate the effects of the replacement of corn silage by up to 100% sugar cane in diets for milking cows. Studied characteristics were milk production and composition, body weight variation, intake of nutrients and economical viability of the diets. Twelve pure and crossbred Holstein milking cows, with potential yield of 5,000 to 7,000 kg of milk per lactation, were distributed in three 4x4 balanced latin square. The animals were maintained in individual stalls, where they were fed ad libitum diets with forage:concentrate ratio of 60:40 twice a day during the 84 experimental days. Treatments consisted in four levels of corn silage substitution by sugar cane: 0; 33.3; 66.6 and 100%. Milk productions were 24.17; 23.28; 22.10 and 20.36 kg/day and corrected 3.5% fat milk productions were 27.00; 24.98; 24.36 and 21.41 kg/day to the levels 0; 33.33; 66.66 and 100% of sugar cane in roughage, respectively. There was not difference in milk composition. Diets intakes, based on dry matter, were 177.90; 169.42; 165.69 and 156.80g/kg0.75 when levels of sugar cane increased in the diets, so, there was a linear reduction. The feeding costs reduced, on R$/day: 4.79; 4.33; 4.00 and 3.58, as well as the incomes, on R$/day: 8.32; 7.60; 6.55 and 5.63, and profits, on R$/day: 3.53; 3.27; 2.55 and 2.05 to the levels 0; 33.3; 66.6 and 100% of sugar cane, respectively. In spite of this, the level of 33.3% of sugar cane in corn silage replacement was technical and economically viable while the levels 66.6 and 100% of substitution were not viable.
feeding costs; intake; milk production; sugar cane
