Institute of Animal Sciences;
Chinese Academy of Agricultural Sciences;
Beijing 100094;
P.R. China;
Guangxi Institute of;
(nimal Science;
Nanning 530001;
P.R. China;
Northwest A&F University;
Yangling 712100;
P.R.China;
Chengde Vocational College;
Chengde 067000;
P.R.China;