The intramuscular fat of Retinta bulls raised on a concentrate feeding system showed higher monounsaturated (587.3 mg/100 g edible meat) and lower polyunsaturated fatty acid (221.0 mg/100 g edible meat) than Retinta bulls that were fed with mixed ration. No feeding system effect on fatty acid profile of fat was observed for the improved breeds. At commercial weight, the percentage of fatty acid desirable for human health was higher (70.3%) from the unimproved breed than the improved breeds (69.1%). The results obtained confirm that genetic background plays an important role in the fatty acid profile of meat from cattle raised with different feeding systems.