All procedures were approved by the University of Zhejing Institutional Animal Care and Use Committee. Two hundred forty male Avian Farms broiler chicks, 1 d of age, were randomly allocated to four treatments,each of which had five pens of 12 chicks per pen. The chicks received the same soybean meal, and FOS was added to the basal diet at 0, 2.0, 4.0, 8.0 g/kg diet at the expense of corn