Grape Seed Proanthocyanidin Affects Lipid Metabolism via Changing Gut Microflora and Enhancing Propionate Production in Weaned Pigs

Background: It is not clear whether dietary grape seed proanthocyanidin (GSP) affects mammalian lipid metabolism via the gut microbiota. Objective: The aim of this study was to evaluate the contribution of the gut microbiota to the effect of dietary GSP. Methods: This study was divided into 3 separate experiments using Duroc x Landrace x Yorkshire pigs (50% male) weaned at day 28 and then fed the same basal diet (NC). In Experiment 1, 90 pigs were fed NC or NC with 250 mg GSP/kg (GSP) or 400 mg betaine/kg [positive control (PC)] for 28 d. In Experiment 2, 30 pigs were fed NC, GSP, or GSP with antibiotics (GSP + Abx) diets for 14 d. In Experiment 3, pigs were fed NC, NC plus 1 g sodium propionate/kg (SP), or NC plus 1 g sodium butyrate/kg (SB) diet for 14 d. Serum biochemical indexes, SCFA concentrations, and microbial composition were determined. Results: In Experiment 1, compared with the GSP group, visceral adipocyte area was higher in the NC (28.6%) and PC (18.2%) groups (P <= 0.05). Colonic propionate and butyrate concentrations were 30.2% and 3.6% higher in the GSP group than in the NC group, respectively (P <= 0.05). In Experiment 2, compared with the GSP group, the NC group had a 108% higher Firmicutes to Bacteroidetes ratio and had 50.4%, 61.2%, and 82.3% lower abundance of Akkermansia, Alistipes, and Bacteroides, respectively (P <= 0.05); antibiotics removed these effects of GSP. In Experiment 3, serum peptide YY was 19.5% higher in the SP group than in the NC group (P <= 0.05), and it did not differ between the SB and NC groups (P > 0.05). Conclusions: GSP affected lipid metabolism in weaned pigs, which is associated with changed gut microbiota and enhanced microbial propionate production.