1. Department of Animal Sciences, The Ohio State University, Columbus 43210
2. USDA-ARS, Fort Keogh Livestock and Range Research Laboratory, Miles City, MT 59301
3. Division of Animal Sciences, University of Missouri, Columbia 65211
4. Departamento de Produção Animal, Faculdade de Medicina Veterinária e Zootecnia-UNESP, Botucatu, SP, Brazil