Four hundred and fifty Avian Farms male broilers chicks with 48±0.3g of live weight were used in an experiment carried out at climatic chambers to evaluate the effect of the metabolizable energy levels (2850; 2925; 3000; 3075 and 3150 kcal of ME/kg), from 1 to 21 days, maintained at high environmental temperature (34ºC and 60% RH). A completely randomized design, with five treatments (ME levels), nine replicates and ten birds per experimental unit, was used. Performance and carcass composition were evaluated and the metabolizable energy requirement of the birds were obtained by linear or quadratic regression, according to the best fit. Weight gain, metabolizable energy intake, and protein and fat depositions in the carcass increased while the feed:gain ratio of the chicks linearly decreased with the treatments. The carcass yield of the birds was not influenced by the dietary ME levels. The dietary ME levels affected the carcass composition and increased the abdominal fat weight of the broiler chicks. The broilers chicks from 1 to 21 days of age, kept under high environmental temperature, require at least an energy:protein ratio of 13.6:1 for better performance and protein deposition in carcass.
broiler chick; high environmental temperature; metabolizable energy
