1. Department of Animal and Food Sciences, Texas Tech University, Lubbock, Texas, USA.
2. Department of Animal Science, South Dakota State University, Brookings, South Dakota, USA.
3. U.S. Meat Animal Research Center, Agricultural Research Service, U.S. Department of Agriculture, Clay Center, Nebraska, USA.
4. Livestock Issues Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Lubbock, Texas, USA.