1. Agriculture and Agri-Food Canada, Lethbridge Research Centre, Lethbridge, AB T2N 4N1, Canada.
2. IRTA, Ruminant Production, Caldes de Montbui, Barcelona 08140, Spain.
3. University of Saskatchewan, Western College of Veterinary Medicine, Saskatoon, SK S7N 5B4, Canada.
4. University of Calgary, Faculty of Veterinary Medicine, Calgary, AB T2N 4N1, Canada.
5. Agri-Health Services Ltd, Airdrie, AB T4A 2G1, Canada.
6. Iowa State University, College of Veterinary Medicine, Ames, IA 50011, USA.