With the improvement of production performance,the physiological function and immunity of dairy cows will decline,  and the risk of various metabolic diseases,such as milk fever,lameness,mastitis,etc.,will also increase.B vitamins are widely involved in various physiological metabolisms of the body.In the process,sufficient supply of B vitamins can ensure the normal physiological metabolism of dairy cows,improve immunity,and reduce the incidence of various metabolic diseases.