Efeito da temperatura ambiente e do sistema de criação sobre as exigências de energia metabolizável para mantença de aves reprodutoras pesadas

This study was conducted to evaluate the effect of the temperature and rearing system on the apparent metabolizable energy requirements for maintenance (MEm) for broiler breeder hens. In the experiment 1, MEm was determined with birds in cages. One hundred-ninety-two birds were housed in climatic chambers at 13, 21 and 30oC. The birds were assigned to four treatments with four replications of four birds each. The treatments were: ad libitum intake, 70, 50 and 30% of ad libitum intake. Comparative slaughter technique was used to determine the retained energy (RE). Maintenance metabolizable energy requirements (MEm) and efficiency of energy utilization (k) were determined by 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 allotted to three temperatures (13, 21 e 30oC) with four replication of eight birds each. The comparative slaughter technique was used to determined the RE and MEm requirements was determined by: EMm=EMI-(RE/k). The MEm requirements for birds in cages were 111.2, 91.5 and 88.5kcal/kg0.75/day and for birds on 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.