1. Shaanxi Key Laboratory of Molecular Biology for Agriculture, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, P. R. China
2. College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan, P.R. China
3. College of Animal Science and Technology, Henan University of Animal Husbandry and Economy, Zhengzhou, Henan, P.R. China
4. Mammalian NutriPhysioGenomics, Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, IL