1. Department of Animal Sciences, Wageningen University, P.O. Box 338, 6700 AH, Wageningen, The Netherlands
2. Animal Production Systems group, Wageningen University, P.O. Box 338, 6700 AH, Wageningen, The Netherlands
3. Adaptation Physiology group, Wageningen University, P.O. Box 338, 6700 AH, Wageningen, The Netherlands
4. Wageningen UR Livestock Research, P.O. Box 65, 8200 AB, Lelystad, The Netherlands