Abstract: 90 35-day-old health Royal chickens were randomly assigned to three groups with five replicates of six Royal chickens per group and the chickens were fed respectively with basal diet supplemented with 0, 500 and 1500 mg/kg eucommia ulmoides oliver for 7 weeks. The results showed that the feed/gain ratio of chickens in the experimental group 1 and 2 were decreased by 4.77% (P＞0.05) and 6.72%(P＜0.05) than that of control group. The percentage of ANAE+ cells and the rate of lymphocyte transformation of the birds in group 2 supplemented with 1500 mg/kg Eucommia ulmoides oliver were significantly increased, the development of spleen were also promoted by eucommia ulmoides oliver addition. Compared with the control group, the ND antibody titers and IgG levels of the chickens in both of the experimental groups tend to be increased slightly during the trial period. 

Key words: eucommia ulmoides oliver; Royal chicken; performance; immune function