1. Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada.
2. Laboratory of Germ Cell Biology, College of Animal Science and Technology, Qingdao Agricultural University, Qingdao, China.
3. Department of Biomedical Science, University of Guelph, Guelph, Ontario, Canada.
4. Departamento de Producción Animal, Universidad de Guadalajara, Zapopan, México.
5. Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario and Children's Health Research Institute, London, Ontario, Canada.