This work was carriedout to evaluate carcass characteristics, physicochemical and fatty acids compositionsof Longissimus muscle from feedlot heifers fed cottonseed hulls (CSH)and soybean hulls (SBH) as forage, and different energy sources: ground corn(COR), corn germ meal (CGM) or whole rice meal (WRM). Twenty-four crossbredheifers (initial body weight of 350 ± 35 kg) were allocated in a completelyrandomized design into three treatments (diets) and eight replications (animals).Heifers were slaughtered after a 24-hour fasting period. Carcasses were identified,weighed and stored in a cold chamber at 2ºC until following morning in orderto perform carcass evaluations. The animals fed the experimental diets did notdiffer as carcass characteristics, the average values for hot carcass dressingwere 51.4%, the loin eye area, 50.8 cm2, and fat thickness, 3.3 mm.The diets also did not influenced the physicochemical composition of Longissimusmuscle, which showed 73.4% of moisture, 23.0% CP, 48.2 mg/100 g of cholesteroland 4.84 kgf/cm3 of shear force. Animals fed with CGM diet showedhigher concentrations of CLA (0.48%), trans-vaccenic acid (7.69%) andworse omega 6/omega 3 ratio in the Longissimus muscle, due to the highersupply of linoleic acid provided by this diet as compared to the others. Animalsfed WRM diet presented higher concentration of stearic acid in the Longissimusmuscle, probably as a result of the higher content of oleic acid in this diet.
