Dietary Glycerol Monolaurate Effect on Growth Performance, Intestinal Barrier Function, and Gut Microbiota in Weaned Piglets Challenged by Lipopolysaccharide

This study aimed to investigate the effects of glycerol monolaurate (GML) on the growth performance, intestinal morphology, inflammatory factors, and gut microbiota of weaned piglets challenged by lipopolysaccharide (LPS). A total of eighteen weaned piglets [Duroc × (Landrace × Yorkshire), average weight 7.54 ± 0.86 kg] were randomly assigned to the following three groups: (1) CON:basal diet; (2) LPS: basal diet + LPS challenge; and (3) LPS_GML: with 1000 mg/kg GML. On day 21, LPS or saline was injected into the piglets via intraperitoneal injection, and samples were collected after 4 h. Results showed that no differences were observed in the average daily gain (ADG), average daily feed consumption (ADFI), and G/F ratio. GML supplementation increased (p < 0.05) the villus height and villus height/crypt depth ratio, the protein expression of claudin-1 and occludin, the mRNA expression of claudin-1, SOD, and GSH-Px, while decreased (p < 0.05) the serum diamine oxidase (DAO) and reactive oxygen (ROS) concentrations and the mRNA expression of IL-1β, IL-6, and IL-8 compared with the LPS group. Moreover, GML regulated LPS-induced gut microbiota dysbiosis by reshaping the composition of gut microbiota, such as increasing (p < 0.05) Actinobacteriota, Lactobacillus amylovorus DSM 20531, Lactobacillus mucosae LM1, and Bifidobacterium boum, while decreasing (p < 0.05) Spirochaetota. Dietary GML supplementation improved the barrier function, reduced the inflammatory factors, and modulated the composition of gut microbiota in piglets challenged by LPS.