The aim of this study was to find the effect of four amino acids (tryptophan (Trp), arginine (Arg), methionine (Met) and threonine (Ther)) supplementation higher than the NRC recommendation on growth performance. A total of 250 day-old male broiler chickens were assigned to five groups in a completely randomized design. Five dietary treatments included one control group (A) and four experimental groups (B: 2 times NRC level of Ther, C: 2 times NRC level of Trp, D: 2 times NRC level of Met, E: 2 Times NRC level of Arg). Growth performance parameters (Body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR)) were measured. Body weight gain, feed intake and feed conversion ratio were significantly influenced by the dietary treatments. Supplementation of arginine, methionine, tryptophan and threonine had the best results respectively. In conclusion, our data suggest that the amino acids requirement of male broiler chicks is higher for growth performance than was suggested by the last NRC committee and the amino acids higher than NRC requirements might have positive effects on health status of broiler chickens.
