Pennsylvania State University, University Park, PA 16802, USA The Ohio State University, Columbus OH 43210, USA USDA-Agricultural Research Service, Pasture Systems and Watershed Management Research Unit, University Park, PA 16802, USA University of Florida, Gainesville, FL 32608, USA Agriculture and Agri-Food Canada, Lethbridge AB, Canada T1J 4B1 Innovation Center for U.S. Dairy, Rosemont, IL 60018, USA University of California, Davis, CA 95616, USA DairyNZ, Hamilton 3240, New Zealand Wageningen University, 6700 AH Wageningen, The Netherlands Food and Agriculture Organization of the United Nations, Animal Production and Health Division, Rome, Italy