1. National Engineering Laboratory for Animal Breeding, Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing, P.R. China
2. Beijing Station of Animal Husbandry, Beijing, P.R. China
3. Beijing LM Pig Breeding Technology Co., Ltd., Beijing, P.R. China
4. Beijing Shunxin Agricultural Co., Ltd., Beijing, P.R. China