The invention of this application provides a method of breeding poultry or a method of improving a feed conversion ratio (FCR), characterized by comprising feeding Bacillus coagulans at a late stage of poultry production in breeding of the poultry, and further provides a feed additive composition for use in improving poultry FCR comprising Bacillus coagulans strain CP3425 (International Accession Number NITE BP-01693) or a derivative or variant thereof.
