1. Taiwan Livestock Research Institute Council of Agriculture, Hsin-Hua, Tainan, 71210 Taiwan, Republic of China
2. Station d'amélioration génétique des animaux, Institut national de la recherche agronomique, Centre de recherches de Toulouse, BP 27, F 31326 Castanet-Tolosan Cedex, France
3. Institute of Biotechnology, National Cheng-Kung University, Tainan, 712 Taiwan, Republic of China