Dietary excess supplementation of limiting amino acids promotes growth performance in broiler chickens through gh and IGF-I

Abstract

The aim of this study was to determine the effects of dietary levels of methionine (Met) and lysine (Lys) on growth, carcass traits, breast meat quality, serum parameters and immunity of broiler chickens. A total of 540 one-day-old broiler chicks were distributed to 6 dietary treatments with 6 replicates of 15 birds in each in a 2x3 factorial approach which consisted of two Met and three Lys levels. The body weight gain (BWG) was increased with the main effect of high Met levels during pre-starter, starter and overall period. In Lys effect, BWG had a tendency to increase during the grower (P<0.09) and overall period (P<0.07). Spleen weight was higher (P<0.01) in high levels of Met, and high Met group has more spleen and thymus weight. Breast meat yield and spleen weight was found higher due to high Lys. Significantly higher pH and redness of breast meat was recorded for the sole effect of Lys levels. Serum glucose was found higher in high levels of Lys with no affect in Met added group. Serum GH and IGF-I levels were found higher (P<0.01) as the main effect of high Met levels as well as IGF-I concentration increased (P<0.01) in serum of chickens fed with the interaction of high density Met and Lys diets as compared to those fed with other diets. The current study suggest, that additional Met and Lys in diet of the current practices may improve body weight which may be due to the stimulation of GH and IGF-1growth factor.