1. Former graduate research assistant, assistant professor, graduate research assistant, and professor, respectively, Department of Agricultural Engineering, University of Illinois, Urbana, IL 61801.
2. Current address: Corn Products International, 6500 Archer Avenue, Bedford Park, IL 60501-1933.
3. Former graduate research assistants and professor, respectively, Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506.
4. Professor, Department of Veterinary Biosciences, College of Veterinary Medicine, University of Illinois, Urbana, IL 61801.
5. Current address: AACC, 3340 Pilot Knob Road, St. Paul, MN 55121-2097.
6. Corresponding author. Fax: 217/244-0323. E-mail: seckhoff@uiuc.edu