Grape seed procyanidins improve intestinal health by modulating gut microbiota and enhancing intestinal antioxidant capacity in weaned piglets

Grape seed procyanidins (GSPs) are polyphenolic compounds extracted from grape seeds and are known for their antioxidant, anti-inflammatory, antimicrobial, and immune modulating properties. As weaning stress in piglets can cause dysbacteriosis and oxidative damage to the intestine, resulting in diarrhea, the present study was conducted to determine whether administering GSPs can enhance intestinal antioxidant capacity and modulate gut microbiota to improve the overall gut health in weaned piglets. A total of 96 crossbred piglets were allocated randomly to four treatment groups; each treatment group comprised six replicate pens with four piglets per pen. Each group was fed one of the four dietary treatments for 28 days: the basal diet (control group) or the basal diet supplemented with 50, 100, or 150 mg/kg of GSPs. One piglet from each pen was euthanized to collect the jejunal mucosae for evaluating the intestinal antioxidant capacity and to collect the digesta of the cecum, colon, and rectum for assessing the succession of the gut microflora and determining the variations in the production of short chain fatty acid (SCFA). Dietary supplementation with GSPs enhanced the jejunal antioxidant capacity in weaned piglets, as evidenced by enhanced superoxide dismutase (SOD) activity (P < 0.001), increased mRNA abundance of superoxide dismutase (Sod1) and catalase (Cat) (P = 0.001 and P = 0.014, respectively), and decreased malondialdehyde (MDA) concentration (P < 0.001). The 100 mg/kg GSPs supplemented group showed enhanced Ace and Chao1 indices of the cecal, colonic, and rectal microflora when compared with those of the control group (P < 0.05), reflecting a rich bacterial community. Supplementing piglet diets with different concentrations of GSPs reduced the relative abundances of Proteobacteria and Anaerovibrio in various intestinal segments. A 100 mg/kg GSPs supplementation raised the abundances of probiotic Prevotellaceae_NK3B31_group and Prevotella_1 in colon and rectum. Dietary GSPs supplementation increased the concentrations of the following SCFAs: acetic acid, propionic acid, and butyric acid in the gut of weaned piglets. In particular, piglets supplemented with 100 mg/kg GSPs presented remarkable increases in the concentrations of acetic acid and butyric acid in the cecum and colon when compared to the control group (P < 0.05). In summary, GSPs might exert salutary effects on the intestine of weaned piglets by enhancing the intestinal antioxidant capacity, modulating gut microbiota composition, and increasing the concentration of microbial metabolites (SCFAs) in the gut.