Abstract: [Objective] This experiment aimed to investigate the effects of compound fermented traditional Chinese medicine feed on the production performance,mammary gland health and physiological metabolism of heat-stressed dairy cows. [Method] Sixty lactating Holstein cows were selected and randomly divided into a control group and three treatment groups （A,B, C）.The four groups were supplemented with 0,50,100 and 150 g/head·d of compound fermented traditional Chinese medicine feed in the basal diet, respectively,with a trial period of 60 days. [Result] Compared with the control group,the respiratory rate and rectal temperature of dairy cows in the treatment groups decreased significantly （P<0.05）;milk yield and milk composition indicators such as milk fat percentage,milk protein percentage and lactose were significantly improved（P<0.05）;the contents of glucose and total protein in serum increased significantly,while the contents of urea nitrogen and heat shock protein 70 decreased significantly（P<0.05）;in terms of antioxidant indicators,the activities of total superoxide dismutase（T-SOD）and glutathione peroxidase（GSH-Px）were significantly enhanced,and the content of malondialdehyde（MDA）was significantly reduced（P<0.05）;in terms of immune indicators,the serum IgG level increased significantly,and the contents of pro-inflammatory cytokines IL-6 and IL-1β decreased significantly（P<0.05）. [Conclusion] The compound fermented traditional Chinese medicine feed can effectively alleviate the adverse effects of heat stress on the production performance and mammary gland health of dairy cows by regulating energy metabolism,enhancing antioxidant capacity and improving immune function,with the best effect at the supplementation level of 150 g/head·d.

Key words: fermented feed, heat stress, dairy cow, traditional Chinese medicine