1. Institute of Agriculture, Natural Resources and Extension, University of Alaska Fairbanks , Fairbanks, AK 99775 , USA
2. Animal Resources Center, University of Alaska Fairbanks , Fairbanks, AK 99775 , USA
3. School of Veterinary and Biomedical Science, University of Nebraska-Lincoln , Lincoln, NE 68583 , USA
4. Department of Animal Science, University of Nebraska-Lincoln , Lincoln, NE 68583 , USA
5. Agricultural Research Service, USDA , Fort Keogh, Miles City, MT 59301 , USA
6. Department of Animal Science, University of Wyoming , Laramie, WY 82071 , USA