[1] Farm Animal Behaviour and Husbandry Section, University of Kassel, Nordbahnhofstraße 1a, Witzenhausen
[2] Thuenen-Institute of Organic Farming, Federal Research Institute for Rural Areas, Forestry and Fisheries, Trenthorst 32, Westerau
[3] Division of Livestock Sciences, Department of Sustainable Agricultural Systems, University of Natural Resources and Life Sciences (BOKU), Gregor-Mendel-Strasse 33, Vienna