1. Bächlerenweg 20, CH-3044 Säriswil, Switzerland
2. Department of Social and Preventive Medicine, Division of Epidemiology and Biostatistics, University of Bern, Finkenhubelweg 11, CH-3012 Bern, Switzerland
3. Swiss Federal Veterinary Office, Centre for Proper Housing of Ruminants and Pigs, CH-8356 Ettenhausen, Switzerland
4. Swiss Federal Veterinary Office, Centre for Proper Housing of Poultry and Rabbits, Burgerweg 22, CH-3052 Zollikofen, Switzerland