A microbial adherence inhibitor in the form of fowl egg antibodies is disclosed, along with the method of making it and methods of using it. The inhibitor functions by substantially preventing the attachment or adherence of colony-forming immunogens in the rumen and intestinal tract of host food animals. The inhibitor is made by inoculating female birds with the immunogen, harvesting the eggs which contain antibodies to the immunogen, drying the egg contents and adding to the feed or water for the host animals. Dependent upon the particular immunogen with which the female bird is inoculated, the egg antibody is used to promote the growth of food animals by improving feed conversion rates by decreasing the waste of dietary protein caused by the presence of certain colony-forming organisms in the animals, and to substantially reduce or eliminate the incidence of illnesses caused by the presence of certain illness-causing colony-forming immunogens, such as E. coli 0157:H7, in meat from food animals, and in other food stuffs.