Discipline: Veterinary Medicine
A feeding trial was conducted to determine the effect of acid protease supplementation of corn-soybean based diets with reduced-crude protein (CP) on the production performance of broiler chickens . Three hundred broiler chicks were randomly distributed to five dietary treatments following a completely randomized design, replicated six times with 10 birds per replicate. The 2% reduction m CP of the broiler diets significantly decreased digestibility of CP and crude fiber (CF) of the starter diet and digestibility of ether extract (EE) and CF of the finisher diet. Average body weight gain at 28 and 42 days and feed conversion ratio (FCR) at 28 days old were significantly depressed by the reduction in CP of the diets. Feed consumption dressing percentage and livability were not markedly influenced by dietary reduction of CP. Supplementation of reduced-CP diets with protease at the rate of 0. 075% and 0.10% significantly improved digestibility of CP and CF of starter and EE of finisher diets. Body weight gain at 28 and 4~ days, and FCR at 28 days of age were significantly improved with 0.075 and 0.10% protease supplementation of reduced-CP diets. At 42 days of age, birds fed the reduced-CP diet supplemented with 0.075% protease had the highest FCR and income over feed and chick cost (IOFCC) compared to birds in the other treatments. Feed consumption, dressing percentage and livability were not significantly influenced by protease supplementation of reduced-CP diets.