1. Institut de la Filière Porcine, La Motte au Vicomte, BP 35104, Le Rheu, France.
2. Centre for Genetic Improvement of Livestock, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada.
3. Canadian Centre for Swine Improvement, Central Experimental Farm, Building No. 75, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada.