This work aimedat determining the influence of roughage proportions and fat source of the dieton characteristics of carcass and comercial cuts of lambs. It was used 24 non-castratedSanta Inês male lambs, ad libitum fed diet with two proportions of roughage(30 and 70%) and fat (no fat, protected fat, and soybean) slaughtered at anavarage body weight of 35.4 kg (± 1.5 kg). Animals fed 30% roughage dietshowed the highest weights and carcass yields. The percentages of posteriorarm and ham were higher in animals fed 30% roughage with no addition of fatsource. Total leg length and internal length were higher in animals fed 70%roughage diet while leg width was higher for those fed 30% roughage diet. Additionof fat source in diets with high percentage of concentrate can increase carcassyields. This effect is higher when protected fat is used regarded to whole soybean.Although diets do not have effect on most of these cuts, the effect on the hamconfirms the influence of the diet on this noble cuts.
