This study was conducted to evaluate the effect of the temperature and rearingsystem on the apparent metabolizable energy requirements for maintenance (MEm)for broiler breeder hens. In the experiment 1, MEm was determined with birdsin cages. One hundredninety-two birds were housed in climatic chambersat 13, 21 and 30ºC. The birds were assigned to four treatments with fourreplications of four birds each. The treatments were: ad libitum intake,70, 50 and 30% of ad libitum intake. Comparative slaughter techniquewas used to determine the retained energy (RE). Maintenance metabolizable energyrequirements (MEm) and efficiency of energy utilization (k) were determinedby the ME intake (MEI) and retained energy (RE) ratio. In the experiment 2,the MEm was determined with birds on the floor. Ninety-six birds were allottedto three temperatures (13, 21 e 30ºC) with four replication of eight birdseach. The comparative slaughter technique was used to determined the RE andMEm requirements was determined by: EMm=EMI-(RE/k). The MEm requirements forbirds in cages were 111.2, 91.5 and 88.5kcal/kg0.75/day and for birdson floor 130.8, 112.9 and 111.0kcal/kg0.75/day at 13, 21 and 30ºC,respectively. Birds raised on floor had MEm higher 21.8% than those in cages,probably due to the energy expenditure for physical activity.
