1. Department of Ethology and Companion Animal Science, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences, Praha, Czech Republic; e-mail:
2. Department of Animal Science and Food Processing, Faculty of Tropical AgriSciences, Czech University of Life Sciences, Praha, Czech Republic; e-mail:
3. Department of Zoology, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic; e-mail: , eidriel@seznam.cz
4. Department of Anthropology, Faculty of Philosophy and Arts, University of West Bohemia, Plzeň, Czech Republic; e-mail: