This experiment was carried out to evaluate the dietary metabolizable energy levels for broilers in the pre-initial growth phase. A total of 280 Avian × Cobb one day old chicks was allotted to warm cages as a completely randomized design with five treatments (2,850, 2,950, 3,000, 3,050, and 3,150 kcal/kg of ME in the diet) and four replicates of 14 birds per experimental unit. Bird weight and diet and orts weights were measured at 1, 4, 7, 10, 14, 18 and 21days old and the performance characteristics determined (average weight gain, feed intake, feed-to-gain ratio) from 1 to 7 and 1 to 21 days. A digestibility assay was performed during the first week between the 4th and 7th days. The results showed that the evaluated ME levels influenced the performance of the birds from 1 to 21 days old, however, the lowest level of ME resulted in worst DM digestibility values. The lowest levels, 2,850 kcal ME/kg, provided better broiler performance, while the 3,115 kcal ME/kg provided better DM digestibility in corn-soybean based diets.
digestibility; digestive organs dimension; nutrient retention; performance
