As a result, diets supplemented with probiotic powder with the same microflora population as FBac+Sac could not improve growth performance (P > 0.05). This may be because 1) fermented feed could degrade large molecule material; 2) microflora may produce substances that are beneficial to broiler growth and health; or 3) the probiotics in fermented feed were activated, whereas the probiotic powders were not. Probiotic powder is unfavorable for retention in the intestines because of the shorter gastrointestinal tract length in broilers.