Lactobacillus agilis in the small intestine reduce abdominal fat deposition in broilers by regulating lipid metabolism

Excessive fat deposition in broilers not only affects the taste and texture of the meat but also reduces feed conversion efficiency and increases breeding costs. Research has indicated that intestinal microorganisms play a crucial role in regulating lipid metabolism and enhancing meat quality. This study found that fecal microbiota transplantation (FMT) from high-weight and low-abdominal-fat chickens to broilers significantly reduced fat deposition and downregulated hepatic lipid synthesis genes (LPL, ACSL1, FADS1) while upregulating catabolism genes (PPARα, HSL) ( P < 0.05). 16S rRNA analysis showed FMT increased beneficial jejunal bacteria like Lactobacillus . Subsequently, a strain of Lactobacillus agilis CIM-3 was isolated from the intestines of high-weight and low-abdominal-fat recipient chickens. Feeding trials confirmed CIM-3 reduces abdominal fat and improves growth performance. It increased cecal populations of SCFA-producing bacteria and elevated serum SCFA levels, while significantly decreased systemic and intestinal inflammatory markers (LPS, IL-1β, IL-8, TNF-α) ( P < 0.05). Mechanistically, CIM-3 upregulated hepatic P-AMPK and HSL and downregulated FAS and LPL ( P < 0.05). In conclusion, gut microbiota, particularly L. agilis CIM-3, plays a key role in regulating broiler lipid metabolism. The strain activates the AMPK signaling pathway by enhancing SCFA production and alleviating inflammation, leading to reduced lipid synthesis and fat deposition.