Abstract: 40 multiparous，lactating Holstein cows were assigned to 4 groups according to milk yield，body weight，parity and days in milk with a randomized design. No difference was existed among groups. the control group diet include straw and concentrated feed, add different levels of alfalfa hay to the test group, analysis of cows production performance and economic benefits of the impact. The results showed that the test group and control group differences in dry matter intake significantly (P＜0.05), experimental group significantly increased milk yield, the difference was significant (P＜0.01),fat percentage reduction, the difference was not significant (P＞0.05), milk protein, non-fat milk solid was significantly increased (P＜0.01). Somatic cell count decreased significantly (P＜0.05).Adding alfalfa to the diet,the quality of milk to be significantly improved. Cost-effectiveness analysis showed that diets supplemented with alfalfa dairy industry can significantly increase the overall efficiency of cultivation, breeding chains.

Key words: alfalfa hay; cow; production performance; economic benefit