ABSTRACT In semi-arid zones, feedlots are considered a tool to minimize the impacts of seasonal forage on the production of sheep meat in the tropics. However, the use of alternative tropical ingredients as substitutes for corn (Zea mays L.) and soybean (Glycine max [L.] Merr.) meal in formulations of confined sheep diets is recurrent. The aim of this study was to evaluate the effect of diets containing corn and soybean meal (CS), corn (CU), cassava (Manihot esculenta Crantz) root (CRU) or spineless cactus (Opuntia ficus-indica [L.] Mill., SCU) associated with urea on the performance, carcass characteristics and meat quality of confined lambs. Forty non-castrated Santa Inês sheep with average age of 150 d and average initial weight of 22.6 ± 2.3 kg were confined in individual pens for 76 d and slaughtered. The diets effects were contrasted by Tukey test. Empty body weight was different among the treatments (P < 0.05) and was 27.3, 25.3, 23.0 and 21.1 kg for the animals fed CS, CU, CRU and SCU, respectively. CS diet presented higher cold carcass weights while SCU diet presented lower cold carcass weights (P < 0.05) (11.37 kg) and higher cooling losses. Luminosity, yellow color intensity and meat moisture content were higher (P < 0.05) in SCU than CS. Liver, skin and internal fat weights were similar (P > 0.05) in CU and CRU, but higher (P < 0.05) than SCU. The replacement of corn and soybean meal for different carbohydrate sources associated with urea reduces the body weight components in confined sheep.