The objective ofthis work was to estimate net energy (NEm) and metabolizable energy(MEm) requirements for maintenance and efficiency of use of metabolizableenergy for maintanence (km) and gain (kg) of grazing Nelloreand crossbred steers. It was used 24 castrated steers, 12 Nellore breed (386kg SBW) and 12 ½ Limousin-Nelore crossbred (397 kg SBW). The comparativeslaughter method was used. In each genetic group, animals were grouped in threesimilar groups: reference; restrict feeding and ad libitum feeding. Thereference group was slaughtered in the beginning of the experiment whereas theothers were slaughtered at the end of it. During the 104 days of the experimentalperiod, the group under restrict feeding had access to pastures for 3.5 hoursdaily whereas the group with ad libitum feeding remained on pasture fulltime. Forage intake was estimated in two trials by using the double-indicatormethod. Values of NEm, MEm, km and kgwere estimated on the basis of empty body weight (EBW) through linear and non-linearmodel fitting. Requirements of NEm and MEm did not differamong Nellore and crossbred animals. In the linear model, the following resultswere obtained: Requirements of NEm = 86 kcal/kg0.75; requirementsof MEm = 136 kcal/kg0.75 and km = 0.63. Kgvalue was higher for Nellore animals (0.39) than for crossbred animals (kg= 0.33). Requirement of net energy of maintenance does not differ among grazingNellores and ½ European-Nellore crossbred. For the same body weight,Nellore animals present greater fat proportion in gain composition than ½European-Nelorecrossbred.
