1. Sustainable Livestock Systems Group, SAC, West Mains Road, Edinburgh, EH9 3JG, UK
2. Animal Breeding and Genomics Group, Wageningen University, Wageningen, the Netherlands
3. Division of Genetics and Genomics, The Roslin Institute, R(D)SVS, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
4. PIC International Group, Ratsteich 31, 24837 Schleswig, Germany