1. Centre for Genetic Improvement of Livestock, University of Guelph, 50 Stone Road E, Guelph, ON, N1G 2W1, Canada.
2. Lactanet, 660 Speedvale Ave., Guelph, ON, N1K 1E5, Canada.
3. Department of Animal Science, Michigan State University, 474 S Shaw Ln, East Lansing, MI 48824, USA.
4. Department of Animal and Dairy Science, University of Wisconsin-Madison, 1675 Observatory Dr., Madison, WI 53706, USA.
5. Institute of Genetics, Vetsuisse Faculty, University of Bern, Bremgartenstr.109a, 3012 Bern, Switzerland.