Abstract: Copper plays a very important role in ruminants,which is an essential trace element for maintaining normal physiological function,biochemical metabolism and growth of ruminants,many enzymes that depend on copper play an important role in ruminants,due to copper deficiency in the herbage of Qinghai-Tibet plateau in cold season,the grazing livestock tended to suffer from copper deficiency,which affects the growth and the improvement of production performance of grazing livestock,for this purpose,a certain amount of copper is needed for grazing livestock,but copper has a low absorption rate in ruminants and affected by many factors,these factors should be researched to improve the absorption efficiency,and lower pollution to the environment.Copper promotes rumen microbial growth,improve the efficiency of rumen fermentation and nutrient digestibility by increasing gas production and energy utilization efficiency,it can also improve the immune function and antioxidant performance of ruminants,eventually copper can improve ruminant production performance,different ruminants or the same ruminants at different physiological stages have different copper requirements,copper should be added according to the nutrient requirements and combined with the actual production.This paper reviewed copper absorption and its affect factors,and the effects of copper on rumen fermentation,nutrient digestibility,immune function,antioxidant performance,production performance of ruminants,in order to provide reference for application of copper in ruminants.

Key words: trace elements; cooper; ruminants; rumen fermentation; antioxidant; immune; production performance