Abstract: Tow experiments, each using four Chinese Yellow Cattle steers, were conducted to study the effect of different level of feed intake on the uric excretion of purine derivatives (PD). The rations used in the two experiments were mixed ration consisting of a roughage and concentrate in the ratio of 40:60(Experiments 1) and 60:40(Experiments 2) respectively. In each experiments, four steers were fed at four fixed levels,100%,80%,60% and 40% of "voluntary intake", using a 4×4 Latin square design. Urine and faeces were collected during the last week (col1ection period) of each feeding period. The apparent digestibilities of OM were not significant among intake level. The daily excretion of PD showed a positive response to the level of intake of DOM. However, the creatinine excretion in urine was no difference at different level intake. PD excretion (Y,mmol/d) was correlated to DOMI (X, g) according to the following equation, Y=0.0225X+10.631（R2=0.954,n=8,p<0.01). The results indicate that PD excretion in the urine can be used as an index for estimating microbial protein supply in Chinese Yellow Cattle.