1. Animal Science, School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia
2. U.S. Department of Agriculture, Agricultural Research Service, U.S. National Poultry Research Center, Athens, GA 30605
3. Inghams Enterprises P/L, Morisset, New South Wales 2264, Australia
4. Baiada Poultry, Pendle Hill, New South Wales 2145, Australia