1. Southeast Poultry Research Laboratory, U.S. National Poultry Research Center, Agricultural Research Service, U.S. Department of Agriculture, 934 College Station Road, Athens, GA 30605
2. Avian Diseases and Oncology Laboratory, U.S. National Poultry Research Center, Agricultural Research Service, U.S. Department of Agriculture, 4279 E. Mt. Hope Road, East Lansing, MI 48823