1. Department of Animal Science; School of Agriculture and Biology; Shanghai Jiao Tong University; Shanghai 200240 China
2. Shanghai Key Laboratory of Veterinary Biotechnology; Shanghai 200240 China
3. Animal Genetics, Bioinformatics and Breeding; University of Copenhagen; Frederiksberg 1870 Denmark
4. Center for Quantitative Genetics and Genomics; Department of Molecular Biology and Genetics; Aarhus University; 8830 Tjele Denmark
5. College of Animal Sciences; Zhejiang University; Hangzhou 310058 China
6. National Station of Animal Husbandry; Beijing 100125 China