1. Poisonous Plant Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, 1150 East 1400 North, Logan, Utah 84341, Grain, Forage, and Bioenergy Research Unit, Agricultural Research Service, U.S. Department of Agriculture, 314 Biochemistry Hall, UNL, East Campus, Lincoln, Nebraska 68583-0737, and Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, Georgia 30602