1. Population Genetics and Embryology, Institute of Genetics and Biotechnology, Tjele, Denmark.
2. Institute of Human Genetics, University of Aarhus, DK-800 Aarhus, Denmark.
3. Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, People's Republic of China.
4. College of Animal Sciences and Technology, Anhui Agricultural University, Hefei City, Anhui Province, People's Republic of China.
5. Veterinary Reproduction and Obstetrics, Faculty of Life Sciences, University of Copenhagen, Frederiksberg C, Denmark.
6. Nutrition and Production Physiology, Institute of Animal Health, Welfare and Nutrition, Faculty of Agricultural Sciences, University of Aarhus, Tjele, Denmark.