1. Department of Animal Sciences, College of Agriculture, University of Missouri, Columbia, Missouri 65211, USA; USDA-ARS. Human Nutrition Research Center, Grand Forks, North Dakota 58202-7166, USA
2. Department of Surgery, School of Medicine, University of Missouri, Columbia, Missouri 65211, USA
3. Department of Animal Sciences, College of Agriculture, University of Missouri, Columbia, Missouri 65211, USA