Lactobacillus johnsonii 3-1 and Lactobacillus crispatus 7-4 promote the growth performance and ileum development and participate in lipid metabolism of broilers.

Long-term use of antibiotic growth promoter (AGP) in animal production is the main cause of antimicrobial resistance of pathogenic bacteria. Therefore, seeking alternatives to AGP is crucial for animal husbandry. Among all AGP alternatives, probiotics are promising candidates. In this study, two strains of lactic acid bacteria, L. johnsonii 3-1 and L. crispatus 7-4, were isolated from the feces of wild Gallus gallus, which exhibited obvious anti-pathogenic activity and improved the growth performance of broilers. Furthermore, we found that these two strains participated in the lipid metabolism of broilers by reducing the content of TC and TG in ileal epithelial cells and up-regulating the liver AMPKα/PPARα/CPT-1 pathway, which affects abdominal fat deposition. In summary, L. johnsonii 3-1 and L. crispatus 7-4 have the potential to be used as AGP substitutes and participate in the lipid metabolism of broilers to reduce abdominal fat deposition. Importantly, our study reveals for the first time that L. crispatus participates in liver lipid metabolism to reduce abdominal fat deposition in broilers.