1. School of Animal Sciences, Virginia Polytechnic Institute and State University , Blacksburg, VA, 24061 , USA
2. Prairie Research Unit, Mississippi State University , Prairie, MS, 39756 , USA
3. Department of Animal Science, Texas A&M University , College Station, TX, 77843 , USA
4. Department of Large Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine , Blacksburg, VA, 24061 , USA