1. Address: Centre for Nutrition Modelling, Department of Animal Biosciences, University of Guelph, Guelph ON, N1G 2W1, Canada
2. Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Gogerddan, Aberystwyth, Ceredigion, SY23 3EB, UK
3. Instituto de Ganadería de Montaña (IGM), CSIC-Universidad de León, Departamento de Producción Animal, Universidad de León, E-24007, León, Spain
4. Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, Scotland, UK
5. Rothamsted Research, North Wyke, Okehampton, Devon, UK