1. Dept. of Food and Resource Economics, University of Copenhagen, Rolighedsvej 25, 1958 Frederiksberg C, Denmark.
2. Dept. of Veterinary and Animal Sciences, University of Copenhagen, Grønnegårdsvej 8, 1870 Frederiksberg C, Denmark.
3. Dept. of Philosophy, Texas A&M University 4237 TAMU College Station, TX 77843, USA.