Effect of dietary supplementation of Tryptophan, Arginine, and Glutamine on growth performance, gut morphology, immune response and meat quality of broiler chicken

Two experiments were conducted to evaluate the supplemental effects of Arginine (Arg), Glutamine (Gln) and Tryptophan (Trp) on growth performance, gut morphology, immune response and meat quality of broilers. In experiment 1, 312 one-day-old Ross×Ross broiler chicks with similar body weight were randomly assigned to 4 dietary treatments (C, control having no amino acids; Arg, a diet with 0.5% L-Arg; Gln, a diet with 0.5% L-Gln and Trp, a diet with 0.5% L-Trp), each containing 6 replicate cages with 13 birds per cage. For further confirmation, experiment 2 considered similar treatments as of experiment 1. Body weight and feed intake were measured weekly. At 2nd and 6th weeks of age, 12 birds per treatment were killed in both experiments to measure gut morphology, serum IgG and IgA and meat quality of broilers. In Expt 1, results showed that dietary Arg, Gln and Trpsupplementation significantly increased (P< 0.05) weight gain and feed intake of broilers than those of control group. In experiment 2, a similar performance trend was obtained compared to Experiment 1. Circulating levels of IgG and IgA were increased with supplementation of AAs in the diet. In both experiments, the breast and drumstick muscles of the group of birds feed amino acids had a higher pH and redness (a*) values, but lower lightness (L*) and yellowness (b*) values of meat. Chicks fed diet with Arg, Gln and Trp had longer villi height and villi to crypt depth ratio, and shorter crypt depth as compared with the control (P<0.05). Thus the addition of Arg, Trp and Gln each at 0.5% in the diet of broiler chicken enhanced growth performance, immunity, gut morphology and meat quality characteristics of broiler.