1. N. E. Cockett, T. L. Shay, D. M. Nielsen, Department of Animal, Dairy and Veterinary Sciences, Utah State University, Logan, UT 84322-4700, USA.
2. S. P. Jackson, Department of Animal Science and Food Technology, Texas Tech University, Lubbock, TX 79409, USA.
3. F. Farnir, S. Berghmans, M. Georges, Department of Genetics, Faculty of Veterinary Medicine, University of Liège (B43), 20 Bd de Colonster, 4000-Liège, Belgium.
4. G. D. Snowder, Agricultural Research Service, U.S. Department of Agriculture, U.S. Sheep Experiment Station, Dubois, ID 83423, USA.