Abstract: Taken the young meat chicken of high pathogenicity with prescriptions1,2 and 3, meanwhile immuning with ND IV,then determinating the level of HI on day 9,20,28,35,40,45.Prescriptions3 could pair the immune body 1.2 titers (log2） on day 7~45, make the uniformity of immune body , lengthen the effective immune body 14~18 days; enhanced leaves the pen body weight 9.5%;enhanced survival rate 3.4%; the material anharmonic ratio reduces 9.0%;the law pouch index and the spleen index in 9th the age and on 45th the age measured all extremely remarkably was higher than the control (P<0.01）;the index of the chest gland on 45th was remakable（P<0.01）;the rate of EAC was extremely remarkably (P<0.01）;the gender rate of ANAE was dominotaly(P<0.01）;the rate of C3b was remarkably enhanced and the rate of IC was lower on the 9th and 45th(P<0.01）.The prescription of Radix Astragali could remarkably enhance the organism immunity function of the young meat chicken.

Key words: radix astragali; broiler; pathogenicity; body fluid immunity; cellular immunity