Abstract: A method of producing a dry whey protein powder fortified with naturally occurring polyclonal antibody IgG to preselected infectious intestinal disease antigens, primarily diarrhea-causing enterotoxigenic Escherichia coli bacteria bearing colonization factor antigens (CFA) I or II and heat labile toxins. The product is made by first immunizing a pregnant ungulate, such as a cow, by administration of antigens of the preselected disease. After parturition the milk from the ungulate is collected and maintained in its natural state. The milk is subjected to a standard cheese-making process which produces coagulated casein and whey. The antibody IgG is carried into the whey, which is concentrated and dried. The resulting dried protein powder contains the antibody. The product may be administered orally to living beings, both humans and other animals, to prevent contraction of the preselected disease and to treat bodies exposed to the disease.