Lack of association between the occurrence of Crohn’s disease and occupational exposure to dairy and beef cattle herds infected with Micobacterium avium subspecies paratuberculosis   Journal of Dairy Science – Vol. 93 No. 6:2371-2376 American Dairy Science Association, 2010   Provided by:   Charles O. Thoen, DVM, PhD Department of Veterinary Micobiology and Preventive Medicine College of Veterinary Medicine Iowa State University Ames, Iowa 50014