Effects of dietary Astragalus mongholicus, Astragalus polysaccharides and Lactobacillus on growth performance, immunity and antioxidant status in Qingjiaoma finishing broilers

Three hundred 21-day-old male Qingjiaoma broilers were randomly assigned to six groups to investigate the effect of dietary stems and leaves of Astragalus mongholicus (AMSLs), Astragalus polysaccharides (APSs), Lactobacillus (Lac) and their combinations on finishing broilers in a 42-day feeding experiment. Supplementary 1% AMSLs, 1 000 mg/kg APSs and 4.5 x 10(10) CFU/kg Lac improved significantly growth performance. Dietary AMSLs, APSs and Lac increased the serum concentrations of immunoglobulins IgA, IgG and complements C3 and C4. Furthermore, AMSLs increased glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities and total antioxidation capacity (T-AOC) and decreased the malondialdehyde (MDA) content in both serum and liver tissue. Compared with individual supplementation, the combination of Lac and AMSLs or APSs increased serum IgA, IgG, C3 and C4 concentrations. The combination of AMSLs and Lac increased serum GSH-Px activity and reduced the MDA content in the serum and liver tissue. These results suggested that AMSLs, APSs and Lac are beneficial feed additives, and the applications of combined Lac and AMSLs or APSs could synergistically improve immunity in broilers.