Effect of Ningxiang pig-derived Lactobacillus reuteri supplementation on the growth performance, lipid metabolism, and gut microbiota of finishing pigs

BACKGROUND: While the pivotal role of the gut microbiota in lipid metabolism has been well established, the specific contributions of bacterial strains isolated from native Chinese pig breeds to lipid metabolic regulation remain largely uninvestigated. The purpose of this research was to investigate the effects of Ningxiang pig-derived L. reuteri XY227 supplementation on growth performance, lipid metabolism, and gut microbiota in finishing pigs. METHODS: Sixteen healthy Duroc × Landrace × Yorkshire (DLY) finishing pigs, with an initial body weight of 63.36 ± 1.28 kg, were randomly assigned to two groups, each with eight replicates. The dietary treatments included a basal diet and a basal diet supplemented with 0.4% L. reuteri XY227 (1 × 10¹¹ CFU/kg of basal diet). The experiment lasted for 50 days. RESULTS: Supplementation with L. reuteri XY227 significantly increased the final body weight (FBW) and average daily gain (ADG) (P < 0.05). Dietary supplementation with L. reuteri XY227 significantly reduced the concentrations of C12:0, C18:1n9c, C20:2, and total monounsaturated fatty acids (MUFA) (P < 0.05) in the dorsal subcutaneous adipose tissue. In the L. reuteri XY227 group, mRNA expressions of sterol regulatory element binding protein-1c (SREBP-1 C), peroxisome proliferator-activated receptor γ (PPARγ), and acetyl CoA carboxylase (ACC) in subcutaneous adipose tissue were notably reduced (P < 0.05). The expression of fatty acid translocase (FAT/CD36) was significantly elevated (P < 0.05). L. reuteri XY227 supplementation increased Cluster of differentiation 36 (CD36) mRNA expression in the jejunum and improved jejunal and ileal the height of villi (P < 0.05). Diet supplemented with L. reuteri XY227 significantly boosted the abundance of Lactobacillus, Enterococcus, and Limosilactobacillus in the ileum mucosa and the valerate content in the colon (P < 0.05). CONCLUSIONS: Collectively, these findings indicate that L. reuteri XY227 supplementation improves growth performance and modulates lipid metabolism, possibly achieved through improvements in intestinal morphology and alteration of the gut microbial community.