The effect of diets containing 0% of wheat bran levels (control buffel grass and cactus pear) contrasted with diets with cactus pear as the only forage source and wheat bran levels (30; 37 and 44%) on nutrient digestibility, feed intake, animal performance, carcass characteristics, and economic analysis was evaluated. Twenty-eight male, non-castrated crossbred lambs (22.6 ± 2.37 kg) were submitted to confinement for 62 days. A completely randomized design was used with four treatments and seven repetitions. Four diets were formulated considering an intended mean daily weight gain of 200 g/animal/day. Means were compared by contrasts using Dunnett test at 5%. Animals fed cactus pear as the only roughage source (diets with 30; 37, and 44% of wheat bran) had lower dry matter intake and nutrient intake, Average Dairy Gain, and total weight gain than animals fed the control diet. Final body weight and slaughter weight of animals fed 44% of wheat bran was similar to the animals fed the control diet. Hot and cold carcass yields were higher in animals fed cactus pear and 30 and 37% of wheat bran. Feeding costs were lower when cactus pear was used as the only roughage source associated with wheat bran and consequently profit was greater. The use of cactus pear as the only roughage source associated with up to 44% of wheat bran is a viable alternative of the diet to confined lambs without modifying carcass characteristics with greater cost:benefit ratio.