Two hundred and eighty-eight Cobb chicks were distributed in a completely randomized design with a split-plot arrangement with six replication of six chicks each, the main plots were in three temperatures (cold, thermo neutral and hot) and the secondary plot were by phase (initial, growing and final). The test diet was produced by replacing the basal diet with test food: 40% soybean meal+60% basal diet. The coefficient of apparent and true metabolizability of dry matter, nitrogen, ether extract of the test diet and apparent and true metabolizable energies (AME and TME) of soybean meal were calculated and energy values were corrected for nitrogen balance (AMEn and TMEn) of soybean meal, in kcal/kg, as fed basis. The mean values of AMEn observed for broiler chicks in cold, thermo neutral and hot temperature were 2110, 2016 and 2022kcal/kg, respectively, and the initial, growing and final phases were 1840, 2052 and 2256kcal/kg, respectively. The metabolizable energy values of soybean meal, the balance and coefficients of metabolizability of the nutrients of the test diet increased with the age of broiler; however, they were not affected by environmental temperature.
broiler; nitrogen balance; metabolizable energy; age; environmental temperature
