Abstract: The study was conducted to investigate the effects of two plant extracts on the immune function of weaned piglets.One hundred and twenty 25-day-old weaned pigs (Large White x Landrace) with similar average body weight were selected and randomly allocated into four groups with three replicates per group and ten piglets per replicate.Piglets in the control group was fed a basal diet,and the others in the experimental groups were fed the basal diets supplemented with 20 mg/kg colistin sulfate and 100 mg/kg bacitracin zinc (antibiotic group),400 mg/kg plant extracts compounds I (plant extract compounds I group),400 mg/kg plant extract compound II (plant extract compound II),respectively.The experiment lasted for 30 days.The results showed that:at 45 days of age,the contents of IgA,IgM,IgG,C₃,C₄,IL-2 and IFN-γ were significantly higher in the two plant extract compounds groups (P< 0.05)，contents of IL-6 and the total number of RBC in two plant extracts compounds groups increased;at 60 days of age,contents of IL-2,IL-6 and IFN-γ in three experimental groups increased (P< 0.05),contents of IgM,IgG,C₃ and C₄  and the total number of RBC in two plant extracts compounds groups increased (P< 0.01),and IgA level increased (P<0.05).The results showed that the two kinds of plant extracts could improve the immune function of weaned piglets.

Key words: plants extract compounds, weaned piglets, immune function