Effects Of Clostridium Butyricum On Lipid Metabolism Of Broiler Chickens And Its Underlying Mechanism

Two experiments were conducted to investigate the effects of Clostridium butyricum on lipid metabolism of broiler chickens and its underlying mechanism.Exp.1To investigate the effects of Clostridium butyricum and Enterococcus faecium on growth performance, lipid metabolism and cecal microbiota of broilers,264one-d-old male Ross308broiler chicks were randomly allocated into4treatments with6replicates in a2x2factorial arrangement and fed4diets with2levels of C. butyricum (0or1×109CFU/kg) and2levels of E.faecium (0or2×109CFU/kg) for42d. There was no significant interaction between C. butyricum and E. faecium on growth performance, lipid metabolism and cecal microbiota of broilers. However, broilers supplemented with E. faecium had lower (P=0.022) serum leptin level at d21and higher (P<0.001) fatty acid synthase (FAS), malic enzyme (ME) and acetyl-CoA carboxylase (ACC) mRNA levels in the liver at d42. Supplementation of C. butyricum improved (P<0.05) average daily feed intake and average daily gain, increased (P=0.016) serum insulin level at21d of age, enhanced (P<0.05) content of intramuscular fat, activities of FAS in the liver and lipoprotein lipase (LPL) in the breast muscle, mRNA expression of FAS, ME and ACC in the liver and LPL in the breast muscle at42d of age, but reduced (P=0.030) cecal Bacteroidetes relative abundance at21d of age. The results of this study indicate that the increased intramuscular fat content of broilers fed C. butyricum as observed may be the result of enhanced lipogenesis.Exp.2The objective of this study was to assess the possibility that C. butyricum and its potential components and metabolites could regulate lipogenesis. Co-culture experiments of Caco-2cells and1×106,1×107, and1×108CFU/ml of C. butyricum were set up to test the cytotoxicity of C. butyricum and the changes of angiopoietin-like protein4(ANGPTL4) mRNA expression. It was found that cell viability was not affected by C. butyricum and ANGPTL4mRNA expression in Caco-2cells was highly induced by1×107CFU/ml of C. butyricum. Co-culture experiment of Caco-2cells and potential components of C. butyricum was set up to monitor any ensuing alteration in ANGPTL4. It was observed that bacterial wall components and potentially secreted substances from C. butyricum could induce ANGPTL4mRNA expression and protein secretion. To determine whether butyrate could affect the ANGPTL4production in Caco-2cells, the role of monocarboxylate transporter1(MCT1) in mediating potentially secreted factors from C. butyricum-induced ANGPTL4production in Caco-2cells and the effect of0.1mM of butyrate on ANGPTL4production in Caco-2cells were investigated. It’s confirmed that butyrate was the factor secreted by C. butyricum that stimulate ANGPTL4production. Besides, the soluble factors secreted by live C. butyricum-Caco-2cells interaction, bacterial wall components-Caco-2cells interaction, and the main metabolites butyrate-Caco-2cells interaction reduced lipogenic genes expression in HepG2cells. The results of this study indicate that1×107CFU/ml of C. butyricum could reduce lipogenesis through the bacterial wall components and the metabolites such as butyrate. In conclusion, C. butyricum per se could reduce lipogenesis through both the bacterial wall components and the metabolites such as butyrate. However, the enhanced intramuscular fat of broilers in C. butyricum-supplemented groups observed in this study may be partially attributed to a changed microecological environment which promoted fat synthesis.