Chitosan Oligosaccharide Reduces Abdominal Fat Deposition by Regulating Cecal Microbiota Composition in Broilers

To illustrate the effects of chitosan oligosaccharide (COS) supplementation on abdominal fat deposition (AFD), lipid metabolism, cecal microbiota composition, and short-chain fatty acids (SCFA) content in the ceca of broilers. Totally, 144 one-day-old male Arbor Acres broilers were randomly allocated into two groups with six replicates and 12 broilers per replicate. The control group (CON) was fed the basal diet; the treatment group was fed the basal diet with 200-mg/kg COS (COS₂₀₀). COS supplementation led to a reduction (p < 0.05) in AFD, serum triglyceride, hepatic high-density lipoprotein cholesterol content, hepatic fatty acid synthase, acetyl-coenzyme A carboxylase gene expression level, and peroxisome proliferator-activated receptor γ gene expression level in abdominal fat (AF). Furthermore, COS supplementation resulted in higher (p < 0.05) relative abundance of cecal Bacteroidetes and Alistipes but lower (p < 0.05) relative abundance of Desulfobacterota, Patescibacteria, Campilobacterota, Deferribacterota, Shuttleworthia, and Erysipelatoclostridium, accompanied by increasing acetic acid, propionic acid, isobutyric acid, caproic acid, and total acid content. The AF weight inversely (p < 0.05) correlated with the relative abundance of Bacteroidota and isobutyric acid content. Overall, COS supplementation reduced AF deposition by inhibiting hepatic fatty acid synthesis, abdominal adipocyte differentiation, and proliferation-related gene expression, which was associated with the changes in cecal microbiota composition and SCFA content.