1. Wageningen Livestock Research, Wageningen University & Research, P.O. Box 338, 6700 AH Wageningen, the Netherlands.
2. CRV, Wassenaarweg 20, 6843 NW, Arnhem, the Netherlands.
3. Topigs Norsvin, Research Center, Schoenaker 6, 6641 SZ, Beuningen, the Netherlands.