1. School of Animal Science, Virginia Tech, Blacksburg, VA 24061, USA
2. Department of Dairy and Food Science, South Dakota State University, Brookings, SD 57007, USA
3. Deparment of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2R3, Canada
4. Unité Mixte de Recherche sur les Herbivores, INRAE, F-63122 Saint-Genès-Champanelle, France
5. Department of Animal Science, South Dakota State University, Brookings, SD 57007, USA
6. Department of Animal Sciences, Food and Nutrition (DIANA), Faculty of Agriculture, Food and Environmental Science, Università Cattolica del Sacro Cuore, 29122 Piacenza, Italy