Effects of Lactiplantibacillus plantarum LP18 on growth performance, immune function, gut microbiota, serum metabolome, and disease resistance in Luhua chicks

This study investigates the effects of dietary supplementation with Lactiplantibacillus plantarum LP18 on growth performance, immune function, gut microbiota, and serum metabolomics in Luhua chicks, as well as their resistance to Salmonella typhimurium (S. typhimurium) infection. Explore the feasibility of LP18 as an alternative to antibiotic growth promoters. Two hundred one-day-old Luhua chicks were randomly divided into four groups: Control group (Control), S. typhimurium-infection group (Sty), LP18 pretreatment group (LP18), and LP18 pretreatment + S. typhimurium infection group (LP18+Sty). The Control and Sty groups were fed a basal diet. The LP18 and LP18+Sty groups were pretreated with 1 × 10⁹ CFU/g of LP18 for 28 days. Subsequently, the Sty and LP18+Sty groups were subjected to continuous S. typhimurium infection for 3 days and euthanized 4 days post-infection. The results demonstrated that LP18 pretreatment increased the average daily gain while reducing the feed conversion ratio of Luhua chicks (P < 0.05). The LP18 pretreatment increased the thymus (P < 0.05) and spleen indices (P < 0.05), as well as serum concentrations of IgA (P < 0.05) and IgG (P < 0.05). Microbiota analysis revealed that LP18 pretreatment modulated the diversity and composition of cecal microflora. Serum untargeted metabolomics revealed 16 significantly differential metabolites between the Control and LP18 groups, which were enriched in arachidonic acid metabolism, terpenoid backbone biosynthesis, and the citrate cycle. Significant correlations were observed between these serum differential metabolites and cecal differential phyla. Furthermore, compared to the Sty group, the LP18+Sty group attenuated S. typhimurium infection-induced pathological lesions in the liver and spleen, along with decreased diarrhea rate (P < 0.001), as well as reduced S. typhimurium colonization in the liver (P < 0.001), heart (P < 0.001), spleen (P < 0.05), and cecum content (P < 0.05). In summary, the study demonstrates that early intervention with LP18 significantly enhances growth performance and immune function in Luhua chicks, improves gut microbiota, modulates serum metabolic profiles, and increases resistance against S. typhimurium infection.