1. Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada, T6G 2P5
2. Animal Science and Technology Station of Guizhou, Guiyang, China, P. R. 550001
3. Agriculture and Agri-Food Canada, Lacombe Research Centre, 6000 C&E Trail, Lacombe, AB, Canada T4L 1W1
4. Alberta Agriculture and Rural Development, Lacombe Research Centre, 6000 C&E Trail Lacombe, AB, Canada, T4L 1W1
5. Department of Animal Sciences, Colorado State University, Fort Collins 80523-1171