The present invention is directed to method for reducing a population of a target pathogen in an animal or within a feedlot. The method involves administering one or more than one controlled release bacteriophage strain or phage component, or both, to the animal, so that the one, or more than one bacteriophage strain is released in vivo and adsorbs to the one or more than one target pathogen, thereby reducing the one, or more than one pathogen from the animal. The controlled release bacteriophage strain or phage component may be administered as a treatment dose prior to further processing of the animal, a treatment dose followed by a maintenance dose, or a maintenance dose, to manage feedlot target pathogens.
