Abstract: In order to study the effect of compound biological bacterium on the performance of broiler, 360 Aiweiyin broilers were chosen and divided them into four groups randomly.The contrasting groups are fed with basic grain ration and the groups for experiment are fed with the basic grain ration with Chlortetracycline(5 mg/kg)，1% and 2% compound biological bacterium.And then compare the performance of the broilers for experiment. The results showed that adding 1% and 2% compound biological bacterium to the basic grain ration can increase the increasing weight per day, the productiveness of fodder, the rate of survival, the rate of slaughter (P<0.05), and Chlortetracycline can be replaced by compound biological bacteriumto increase the performance of broiler.

Key words: compound biological bacterium; Chlortetracycline; broiler; performance