1Department of Agriculture and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada T6G 2P5; 2Agriculture and Agri-Food Canada, Lacombe Research Centre, 6000 C&E Trail, Lacombe, Alberta, Canada T4L 1W1; 3Alberta Agriculture, Food and Rural Development, Western Forage Beef Group, Lacombe Research Centre, Lacombe, Alberta, Canada. T4L 1W1. Received 27 January 2003, accepted 28 Au...