Combined supplementation with Lactobacillus sp. and Bifidobacterium thermacidophilum isolated from Tibetan pigs improves growth performance, immunity, and microbiota composition in weaned piglets.

Probiotics, such as Lactobacillus and Bifidobacterium, promote growth in piglets by modulating gut microbiota composition and improving the host immune system. A strain of Lactobacillus sp. and Bifidobacterium thermacidophilum were previously isolated from fresh feces of Tibetan pigs. The effects of these isolated strains on growth performance, intestinal morphology, immunity, microbiota composition, and their metabolites were evaluated in weaned piglets. Thirty crossbred piglets were selected and fed either a basal diet (CON), a basal diet supplemented with aureomycin (ANT), or a basal diet supplemented with Lactobacillus sp. and B. thermacidophilum (LB) for 28 d. The piglets in the ANT and LB groups had significantly higher body weight gain than those in the CON group (P < 0.05). Piglets in the ANT and LB groups had regularly arranged villi and microvilli in the small intestine. Furthermore, they had improved immune function, as indicated by decreased serum concentrations of inflammatory cytokines (P < 0.05), improved components of immune cells in the blood, mesenteric lymph nodes, and spleen. Additionally, metagenomic sequencing indicated a significant shift in cecal bacterial composition and alterations in microbiota functional profiles following Lactobacillus sp. and B. thermacidophilum supplementation. Metabolomic results revealed that the metabolites were also altered, and Kyoto Encyclopedia of Genes and Genomes analysis revealed that several significantly altered metabolites were enriched in glycerophospholipid and cholesterol metabolism (P < 0.05). Furthermore, correlation analysis showed that several bacterial members were closely related to the alterations in metabolites, including Bacteroides sp., which were negatively correlated with triglyceride (16:0/18:0/20:4[5Z,8Z,11Z,14Z]), the metabolite that owned the highest variable importance of projection scores. Collectively, our findings suggest that combined supplementation with Lactobacillus sp. and B. thermacidophilum significantly improved the growth performance, immunity, and microbiota composition in weaned piglets, making them prospective alternatives to antibiotics in swine production.