Effects of Hypericum attenuatum Choisy extract on the immunologic function and intestinal microflora of broilers under oxidative stress

This study investigated the impact of Hypericum attenuatum Choisy extract ( HYG ) on immunological function and the cecum microflora in broilers. A total of 240 one-day-old AA broilers were randomly divided into 5 groups with 6 replicates of 8 broilers each: 1) the CN group, in which broilers were injected with saline and fed a basal diet; 2) the PC group, in which broilers were injected with lipolyaccharide (LPS) LPS ) and fed a basal diet; 3) the HYG1 group, in which broilers were injected with LPS and fed a 400 mg/kg HYG-supplemented diet; 4) the HYG2 group, in which broilers were injected with LPS and fed a 800 mg/kg HYG-supplemented diet; 5) the HYG3 group, in which broilers were injected with LPS and fed a 1,200 mg/kg HYG-supplemented diet. Broilers were injected with 1 mg/kg LPS or the same amount saline 12 hours before sampling on d 21 and 42. The results revealed that dietary 400 mg/kg HYG supplementation alleviated spleen index and thymus index abnormalities, balanced the disturbance of serum immunoglobulin (Ig) Ig ) M and IgA levels, and regulated the cytokine balance in the serum, liver, spleen and jejunum tissues included induced by LPS. Dietary supplementation with 400 mg/kg HYG also downregulated the relative expression of the inhibitor of kappa B kinase alpha ( IKKa ) and interleukin (IL) IL )-6 mRNAs in the liver and upregulated the relative expression of the inhibitor kappa B alpha ( IkBa ) and IL-10 mRNAs in the spleen. Dietary HYG improved the cecal microflora balance at 42 d by increasing the relative abundance of beneficial bacteria, such as Alistipes and Phascolarctobacterium, , while reducing the relative abundance of harmful bacteria, such as Helicobacter and Colidextribacter. . Spearman correlation analysis revealed a negative correlation between activation of the NF-KB inhibitory pathway in the liver and the presence of Phascolarctobacterium, Erysipelatoclostridium, Subdoligranulum and Parabacteroides. . Conclusions: The incorporation of 400 mg/kg HYG into the diet was optimal in improving broiler immunological function.