Chickens in Group A and B were not injected with astragalus polysaccharide(APS). Each chicken in Group C and D was injected with 5?mg and 10?mg of APS per day from days 26 to 31,respectively.

• A、B组未用黄芪多糖(APS)处理,C、D组从攻毒当日起连续胸肌注射APS 6 d,剂量分别为每只鸡5 mg和10 mg。