1. Laboratory of Molecular Recognition and Antibody Technology, Wageningen University, P.O. Box 8123, 6700 ES Wageningen, The Netherlands
2. Adaptation Physiology Group, Wageningen University, P.O. Box 338, 6700AH Wageningen, The Netherlands
3. Animal Nutrition Group, Wageningen University, P.O. Box 338, 6700AH Wageningen, The Netherlands.