1. Department of Biomedical Sciences, Animal Reproduction and Biotechnology Laboratory, Colorado State University, Fort Collins, Colorado.
2. Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado.
3. Department of Animal Sciences, University of Wyoming, Laramie, Wyoming.
4. College of Public Health, University of South Florida, Tampa, Florida.
5. Department of Animal and Range Sciences, South Dakota State University, Brookings, South Dakota.