Effects of high-concentrate diet supplemented with grape seed procyanidins on the colonic fermentation, colonic morphology, and inflammatory response in lambs

This study aimed to investigate the effect of grape seed procyanidins (GSPs) on the local inflammation of the colonic epithelium of lambs fed a high-concentrate diet. A total of 48 1/2 Dorper x 1/2 thin-tailed Han ram lambs were randomly assigned to 4 groups and treated with a 70:30 concentrate: forage basal diet (CON), or a basal diet supplemented with 10 (10GSPs), 20 (20GSPs), or 40 (40GSPs) mg/kg BW/d GSPs. The results showed an increasing trend (P = 0.060) in the pH value of the colonic chyme with an increase in the concentration of the GSPs supplements. The concentrations of acetate and propionate in the 20GSPs and 40GSPs groups were lower (P < 0.05) than those in the CON and 10GSPs groups. As the dietary supplementation with GSPs increased, the concentration of lipopolysaccharides (LPS) in colonic digesta tended to decrease (P = 0.070). The LPS and LPS-binding protein (LBP) concentrations in the peripheral blood plasma of lambs in the 20GSPs and 40GSPs groups were lower (P < 0.05) than those in the CON and 10GSPs groups. The protein abundance of claudin-1 in the colonic epithelium in 20GSPs and 40GSPs groups was upregulated (P < 0.05) compared with the CON group. The gene expression of the Toll-like receptor 4 (TLR4) and tumor necrosis factor (TNF)-alpha, the protein abundance of TLR4 and nuclear factor kappa B (p65), and the activity of myeloperoxidase (MPO) in the colonic epithelium were significantly downregulated (P < 0.05) in the 20GSPs and 40GSPs groups compared with those in the CON and 10GSPs groups. Furthermore, the interleukin (IL)-1 beta concentration in colonic tissue of 20GSPs and 40GSPs groups were lower (P < 0.05) than that of the CON group, and the IL-2, IL-6, and TNF-alpha concentrations in the 40GSPs were also lower (P < 0.05) than those in CON treatment. Additionally, compared with the CON and 10GSPs groups, 40GSPs increased the total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-Px) activities and decrease the level of malondialdehyde (MDA) in colonic tissue (P < 0.05). Therefore, a basal diet supplemented with 20 and 40 mg/kg BW/d GSPs were found to improve the antioxidant potential of the colonic epithelium and alleviate the local inflammation and disruption of the colonic epithelium in lambs induced by a high-concentrate diet.