Objective: The study aimed to evaluate sugarcane bagasse as roughage in lactating cow on feed intake, digestibility, ingestive behavior, milk production and composition, and microbial protein synthesis. Methods: Ten Girolando cows at initial body weight of 450 +/- 25.6 kg and at 143.7 +/- 30.7 days in milk were assigned in two 5x5 Latin square designs. Five 21-day experimental periods were adopted (1 degrees to 14-day: diets adaptation period; 15 degrees to 21-day: data collection and sampling period). The diets consisted of four different levels of sugarcane bagasse (45\%, 50\%, 55\%, and 60\%) and a control diet, commonly adopted in the region, based on spineless cactus (25\% sugarcane bagasse), formulated to meet 12 kg/d milk yield. Results: The dry matter (DM), organic matter (OM), and total digestible nutrients intakes and DM and OM digestibilities observed for 45\% and 50\% bagasse inclusion were similar to control diet, while that 55\% and 60\% bagasse inclusion were lower. Cows fed control diet, and bagasse diets of 45\%, and 50\% levels had the nutritional requirements attended, that guaranteed 12 kg/d of milk yield. The crude protein intake and digestibility of cows fed 45\%, 50\%, and 55\% of bagasse inclusion were similar to control diet. The neutral detergent fiber (NDF) intake and digestibility differ for all bagasse diets related to control diet, while the nonfiber carbohydrates intake and digestibility for cows fed 45\% of bagasse were similar for con-trol diet. The intakes and digestibilities of nutrients decreased linearly in function of bagasse inclusion; NDF and indigestible NDF intakes did not vary. The ruminating time, feeding and rumination efficiency, microbial protein synthesis and milk yield decreased linearly with sugarcane bagasse inclusion. Conclusion: Sugarcane bagasse decreases milk production; however, its inclusion level in between 45\% to 50\% associated to concentrate could replace diets based on spineless cactus for crossbred dairy cow's producing 12 kg/d of milk.