RESUMO
In order to evaluate the effects of different levels of energy and methods of formulation of Amino Acid (AA) requirements of diets, this experiment was conducted using 392 broiler chicks. The experiment was carried out using a complete randomize block design with 7 levels of energy 3175, 3075, 2975, 2875, 2775, 2675 and 2575 kcal kg(-1) for grower diet and 3225, 3125, 3025, 2925, 2825, 2725 and 2625 kcal kg(-1) for finisher diet and two methods of formulation of diets AA requirements (total and digestible) as a factorial arrangement. Results showed that by increasing level of energy feed intake, body weight and FCR were promoted in grower diet (p<0.05). Effect of decreasing level of energy up to 2725 and 2825 kcal kg(-1) was not significant on body weight and FCR in finisher diet, respectively. Formulating of diet based on total or digestible AA affected feed intake and FCR in finisher diet (p<0.05). Interaction effect of independent factors affected on body weight in grower diet (p<0.05). Decreasing level of energy increased gastrointestinal tract percentage weight (p<0.05). Formulation of diet based on digestible AA decreased gastrointestinal tract percentage weight (p<0.05). Abdominal fat decreased significantly as ME content of diets decreased. Results showed that it's possible to reduce the level of energy up to 3175 kcal kg(-1) in grower and 2725 kcal kg(-1) in finisher diet for giving the best and economical performance response. Formulation of diet based on digestible AA in finisher diet resulted in promotion of performance.
