The results showed no significant different between groups in performance parameters such as body weight and FCR. However, the present work showed highest dose of lysine, methionine, threonine and tryptophan supplementation for 42 days may be improved feed intake and immune response of chicken against Gumboro disease vaccination. | Effects of methionine threonine and tryptophan on growth performance and serum antibody titers to Gumboro disease of color-feathered chickens