1. Department of Companion Animal and Special Species Medicine, College of Veterinary Medicine, 4700 Hillsborough St., Raleigh, North Carolina 27606, USA
2. National Biological Service, North Carolina Cooperative Fish and Wildlife Research Unit, North Carolina State University, Raleigh, North Carolina 27695, USA
3. Extension Poultry Science, College of Agriculture and Life Sciences, North Carolina State University, Scott Hall Box 7608, Raleigh, North Carolina 27695, USA