Effect And Mechanism Of Sodium Butyrate On Fat Deposition In Broilers

Gut microorganism are closely related to the health of the host.Intestinal microbial structure disorder can lead many diseases,including obesity,inflammation,nervous system diseases.Diet,such as dietary fiber,probiotics,probiotics,antibiotics,etc.,can affect the structure and abundance of intestinal flora.Intestinal microbial metabolites,such as short chain fatty acids(SCFAs)and bile acids,play a vital role in the metabolic activities of organisms.Of the three main types of SCFAs,the beneficial effects of butyrate on health have been most studied in mammals.As a feed additive,coated sodium butyrate(SB)can release butyrate in the hindgut and participate in the regulation of animal growth and metabolism.Mammalian studies have shown that butyate can affect the body's fat metabolism.Fat metabolism of chicken is quite different from that of mammals.However,the effect of sodium butyrate on fat deposition in broilers and its molecular mechanism are still unclear.In this study,the effect and its molecular mechanism of sodium butyrate(SB)on fat deposition in broiler chickens were investigated by animal experiment and in vitro cell experiment.The animal trials were divided into two groups,Control group: a basal diet supplemented with polyacrylic acid resin(the coating material).SB group: a basal diet supplemented with 1g/kg sodium butyrate coated with polyacrylic acid resin II(70% of sodium butyrate was protected).Feeding was started at the age of 1 day,samples were collected at 21 and 42 days of age,In vitro experiments were performed using chicken hepatocytes and adipocytes,different concentrations of sodium butyrate were added to explore the mechanism of low and high concentrations of butyrate.This study found that in animal experiments,sodium butyrate can significantly reduce abdominal fat rate and liver index in chicken,and reduce fat deposition in liver and adipose tissue,reduce serum alanine aminotransferase(ALT),triglyceride(TG)and total cholesterol(TCH)level.The results of 16 S rRNA sequencing showed that sodium butyrate changed the structure of intestinal bacteria at the phylum and genus levels.The abundance of Megamonas,Coprococcus and Coprobacter was significantly increased by adding sodium butyrate to diet,Bacteroidesand and Lactobacillus were enriched,decreased the abundance of Helicobacter,Campylobacter,Butyricicoccus,Barnesiella and Bifidobacterium.Gas chromatograph mass spectrometer(GC–MS)analysis showed that compared with the control group,the content of butyrate in the caecal contents of sodium butyrate group tended to increase.In vitro experiments showed that lower or higher butyrate doses inhibited or enhanced fat deposition,respectively,in chicken hepatocytes and adipocytes.The effect of butyrate on fat deposition was more evident in adipocytes than in hepatocytes.The results of oil red O and Bodipy staining and TG determination,the lipid decreased at a lower concentration(0.01mM)of sodium butyrate,and the TG showed a trend of decrease.At a higher concentration(1mM)of sodium butyrate,the cell number decreased significantly and the lipid droplets become bigger.The EdU and CCK-8 assays showed that butyrate dose-dependently decreased preadipocyte proliferation and cell viability.SiRNAs specific to the short chain fatty acids receptors were used to down-regulate their expression.At a lower sodium butyrate concentration(0.01mM),free fatty acid recepter 2(FFAR2)and free fatty acid recepter 3(FFAR3)mediated the suppression of fat accumulation by butyrate in preadipocytes/adipocytes.At a higher concentration(1mM),the stimulation of fat deposition by sodium butyrate was partially achieved via a reduction in histone deacetylase activity(HDAC).Actually,The total fat accumulation was also decreased at hinger concentrations due to its suppression on the cell proliferation.Neither extracellular regulated protein kinases(ERK)nor AMP-activated protein kinase(AMPK)signaling was involved in the role of butyrate in fat accumulation.Collectively,butyrate at lower or higher concentrations exerts double-edged effects on fat deposition in chickens via different mechanisms.Excessive fat deposition will reduce the feed conversion rate of broilers,affect the quality of chickens,and seriously increase the mortality of chickens.This paper revealed the effect of butyrate,a metabolite of intestinal microorganisms,on fat deposition in broilers and its molecular mechanism.The results of this study can enrich the theory of regulation of fat metabolism in poultry and provide theoretical support for the application of sodium butyrate as a feed additive in poultry production.