1. Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, Pennsylvania.
2. Department of Animal Science, The Pennsylvania State University, University Park, Pennsylvania.
3. Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, Iowa.
4. Department of Food Science, The Pennsylvania State University, University Park, Pennsylvania.
5. Department of Biology, Gettysburg College, Gettysburg, Pennsylvania.