1. College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, China
2. Department of Animal & Avian Sciences, University of Maryland, College Park, MD 20742, USA
3. Department of Animal Breeding and Genetics, College of Animal Sciences, China Agricultural University, Beijing 100193, China
4. Bovine Functional Genomic Laboratory, Animal and Natural Resources Institute, USDA-Agricultural Research Service, Beltsville, MD 20705, USA
5. Standerds Division, USDA-Agricultural Marketing Service-National Organic Program, Washington, DC 20250, USA