The objective of this experiment was to evaluate the effects of diets with corn silage or with sugar cane + sunflower seed and influence of sexual categories of fedlot young cattle on the performance and economic results of this production system. Thirty animals of Canchim breed ( 10 young bulls, 10 castrated males and 10 females) averagfing 15 months old and 289 kg BW were housed in individual stalls, for 105 days and weighted in the beginning of the experiment and every 35 days. At the end of the feedlot, all the animals were slaughtered in commercial frigorific and measures of carcass characteristics were made. Young bulls showed higher nutrient intakes as compared to females, in absolute values and in relation LW values. The castrated males presented intermediary values, not differing from young bulls and females. Young bulls presented higher daily weight gain and muscular development, represented by the largest rib eye area. They were also more efficient as for feed conversion and carcass yield. No effect was observed for diets on the ingestion of nutrients, except for EE, that was higher for the diet with sugarcane + sunflower seed, with more of this nutrient. Diets also did not influence performance of the animals. Diet with corn silage showed more economically viable to raised young cattle in fed lot finishing. Young bulls were the animals more adequate for the exploration of young cattle in feedlot, independently of diet.
