1. Institute of Veterinary Bacteriology, National Reference Center for Poultry and Rabbit Diseases, Vetsuisse Faculty, University of Zurich, Switzerland (Albini, Sigrist, Güttinger, Hoop, Vögtlin)
2. Animal Genetics Group, Vetsuisse Faculty Zurich and Department of Animal Sciences, Swiss Federal Institute of Technology, Zurich, Switzerland (Schelling)