College of Life Science;
Zhongkai University of Agriculture and Technology;
Guangzhou 510225;
P.R.China;
Department of Animal Science;
South China Agricultural University;
Guangzhou 510642;
P.R.China;
Bureau of Animal Husbandry of Tiane County;
Guangxi Zhuang Autonomous Region;
Tiane 547300;
P.R.China;