In this study, firstly carried out the research methord determining the content of alfalfa saponins. The unifactor experiment and orthogonal trail design were adopted to opitimize extraction method of total of alfalfa saponins. At the same time studied contents of alfalfa saponins in different alfalfa varieties, different breeding period and different parts of the plants. At last, Four Inner Mongolian semi-fine wool wethers with permanent ruminal cannulas were fed a diet with concentrate/roughage...