1. Department of Nutrition and Biotechnology of Ruminants, Instituto de Investigaciones en Ciencias Veterinarias, Universidad Autónoma de Baja California , Mexicali, Baja California 21386 , México
2. Department of Animal Science, University of California , Davis 95616, California , USA
3. Instituto de Ciências Sociais, Educação e Zootecnia, Universidade Federal do Amazonas , Parintins 69152240 , Brazil
4. Cooperative Extension, Division of Agriculture and Natural Resources, University of California , Holtville 92250, California , USA