The antibiotic-free technology involves extracting antibodies from egg yolks from pathogen-free hens or female chickens that have been hyperimmunized — injected with a vaccine that contains inactivated pathogenic organisms. In the USDA study, one-day-old chickens were given feed mixed with spray-dried egg yolk powder prepared from hens hyperimmunized with multiple species of the parasite Eimeria, which causes coccidiosis. The chickens were then exposed to live coccidia parasites. Chickens that had received the hyperimmune egg yolk antibodies gained more weight and shed significantly fewer Eimeria in their feces. The treated birds also had less gut lesions than chickens that did not receive the treatment.
Avian immunologist Hyun Lillehoj at the Agricultural Research Service Animal Parasitic Diseases Laboratory in Beltsville, Md., partnered with Agricultural Research Service colleagues, university scientists and collaborators from the Mexican company Investigacíon Aplicada S.A. on the studies.