Dietary Moutan Cortex Radicis Alters Serum Antioxidant Capacity, Intestinal Immunity and Colonic Microbiota in Weaned Piglets

Background: Moutan cortex radicis (MCR), as a common traditional Chinese medicine, has been widely used as antipyretic, antiseptic and anti-inflammatory agent in China. However, few studies have evaluated the positive effects of MCR, as a new feed additives, on alleviating weaning stress and improving intestinal health and microbiom in pigs. This study aimed to investigate the effect of dietary MCR supplementation on serum antioxidant capacity, intestinal morphology, anti-inflammatory mechanism, and microbiota in weaned piglets.Results: Supplemental 2000 mg/kg and 4000 mg/kg MCR increased (P < 0.05) the final body weight, ADG and ADFI of weaned piglets, and 2000 mg/kg MCR diet significantly decreased (P < 0.05) the F/G ratio and increased (P < 0.05) serum catalase activity compared with CON group. Also, the villus height and crypt depth in the ileum and the concentrations of total SCFA, acetic acid, butyric acid and valeric acid in the colonic contents were higher (P < 0.05) in the 2000 mg/kg and 4000 mg/kg MCR diets than CON group. Dietary MCR supplementation at 4000 mg/kg MCR significantly increased (P < 0.05) total antioxidative capability and the crypt depth in the jejunum but decreased (P < 0.05) the mRNA expression levels of Interferon γ, tumor necrosis factor-α, interleukin-1β, inhibiting kappa B kinase β (IKKβ), inhibiting nuclear factor kappa-B (IκBα) and nuclear factor kappa-B (NF-κB) in the jejunum and ileum. Supplemental 8000 mg/kg MCR had the higher total antioxidative capability and catalase activity in the serum but decreased (P < 0.05) the villus height and crypt depth in the jejunum compared with the CON group. MCR addition reduced (P < 0.05) serum malondialdehyde content, and tended to increase the mRNA expression of zonula occludens-1 in the ileum (P = 0.066) compared to the CON group. Microbiota sequencing identified the microbial richness indices (Chao1, ACE, and observed species), the relative abundances of Firmicutes and Lactobacillus were increased (P < 0.05), and the relative abundances of Bacteroides, Parabacteroides, unidentified_Lachnospiraceae and Enterococcus were reduced (P < 0.05) by MCR supplemented. Microbial metabolic phenotypes analysis also showed that the richness of aerobic bacteria and facultative anaerobic bacteria, oxidative stress tolerance, and biofilm forming were significantly increased (P < 0.05), and the richness of anaerobic bacteria and pathogenic potential of gut microbiota were reduced (P < 0.05) by MCR treatment. Conclusions: In antibiotic-free diets, MCR supplementation improved growth performance and serum antioxidant capacity, alleviated intestinal inflammatory by inhibiting IKKβ/IκBα/NF-κB signaling pathway and affecting intestinal microbiota in weaned piglets.