[1] USDA ARS, Natl Anim Dis Ctr, Preharvest Food Safety & Enter Dis Res Unit, Ames, IA 50010 USA
[2] Univ Georgia, Dept Poultry Sci, Athens, GA 30605 USA
[3] Cornell Univ, Coll Vet Med, Ithaca, NY 14850 USA
[4] Iowa State Univ, Coll Vet Med, Vet Diagnost & Prod Anim Med, Ames, IA 50011 USA