ABSTRACT
Background: Despite the fact that immune responses are influenced by dietary nutrients, feed formulation is mainly based on the productive responses, so the immunity indexes were ignored
Objectives: This study was carried out to determine the effects of diets formulation based on different expression systems of energy and amino acids of feeds and requirements on performance and immune responses of Arian chicks
Methods: A total of 1440 Arian chicks were fed eight diets arranged in a 2x2x2 factorial design with 2 systems of energy expression [AMEn and TMEn], 2 methods of amino acids content of feeds [TAA[f] and DAA[f] and 2 methods of amino acids requirement [TAA[r] and DAAr[r] from 1 to 42 days of age. Each treatment was replicated six times with each replicate consisting of 15 males and 15 females
Results: The results showed that when the Feed formulation was based on TMEn and DAA, the productive parameters increased compared with AMEn and TAA [p<0.05]
Conclusions: Selection for increase the growth rate in poultry, improve metabolic and physiological processes in order to use the feed. Therefore, lower proportions of nutrients will be allocated to other vital systems. However, the most suitable immune responses were observed in chicks that were fed diets which were set based on AMEn and received high level of amino acids. There is a negative correlation between immune responses and productive parameters. It is recommended that in normal conditions TMEn and DAA be used and in stress conditions AMEn and DAA[p]xTAA[r] be added to feed formulation