effects of different expression methods of diet metabolizable energy and amino acids on productive and metabolic parameters of arian broilers

a total of 1440 arian chicks were used in this study to determine the effects of diet formulation methods on performance and blood parameters of arian chicks. eight diets were arranged in a 2×2×2 factorial design with 2 methods of energy expression (apparent (amen) and true (tmen) metabolizable energy corrected to n equilibrium), 2 methods of amino acids content of feeds (total (taaf) and digestible (daaf)) and 2 methods of amino acids requirement (total (taar) and digestible (daar)) from 1 to 42 days of age. each treatment was replicated in six times containing of 15 males and 15 females. the results showed that the productive parameters increased when the feed formulation was based on tmen and daa, compared to amen and taa methods (p<0.05). the values of blood parameters related to energy metabolism in a way that chicks were fed diets which formulated based on tmen had high levels of glucose, triglycerides, cholesterol and hdl. the values of blood parameters associated with protein metabolism in a way that; use of daaf method increased the total protein, globulin and urea of serum. uric acid, albumin and ldl were not affected by any of the systems. therefore use of tmen method and digestibility coefficients of amino acids to feed formulation could improve metabolic efficiency and so productive parameters