1. Departamento de Producción Animal, Facultad de Agronomía, UBA, Buenos Aires, Argentina
2. Department of Animal Science, Michigan State University, East Lansing 48824
3. USDA/ARS, U.S. Meat Animal Research Center, Clay Center, NE 68933
4. Consejo Nacional de Investigaciones Científicas y Técnicas- CONICET. Argentina
5. Department of Fisheries and Wildlife, Michigan State University, East Lansing 48824