1. The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush, Midlothian, Scotland, UK;
2. Dipartimento di Agronomia Animali Alimenti Risorse Naturali e Ambiente, University of Padova, Legnaro, Italy;
3. Dipartimento di Scienze Medico-Veterinarie, University of Parma, Parma, Italy;
4. Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand