1. AgroSup Dijon, Higher National School of Agriculture and Food Science, 21079 Dijon, France
2. Epidemiology, Health and Welfare Unit, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), 22440 Ploufragan, France
3. Department of Animal and Veterinary Sciences, Aarhus University, DK-8830 Tjele, Denmark