摘要Intensive selective breeding for high growth rate and body weight cause excess abdominal fat in broilers.Gut microbiota and folic acid were reported to regulate lipid metabolism.A total of 210 one-day-old broilers were divided into the control(folic acid at 1.3 mg/kg)and folic acid groups(folic acid at 13 mg/kg)to illustrate the effects of folic acid on growth performance,abdominal fat deposition,and gut microbiota,and the experiment lasted 28 d.Results revealed that dietary folic acid addition decreased abdominal fat percentage(P＜0.05)and down-regulated genes expression related to cell proliferation and differentiation in abdominal fat including IGF1,EGF,C/EBPα,PPARγ,PLIN1,FABP4 and PCNA(P＜0.05).Folic acid addition decreased caecal Firmicutes-to-Bacteroidetes ratio(P＜0.01)and increased the proportions of Alistipes,Oscillospira,Ruminococcus,Clostridium,Dehalobacterium and Parabacteroides(P＜0.05).Caecal acetic acid,and propionic acid contents were found to be higher under folic acid treatment(P＜0.05),which were negatively related to genes expression associated with adipocyte proliferation and differentiation(P＜0.05).Ruminococcus was positively correlated with caecal acetic acid content,and the same phenomenon was detected between propionic acid and Oscillospira and Rumi-nococcus(P＜0.05).Acetic acid and Oscillospira were identified to be negatively associated with abdominal fat percentage(P＜0.05).In conclusion,our data demonstrated that dietary supplementation of folic acid reduced fat deposition in broilers by inhibiting abdominal adipocyte proliferation and dif-ferentiation,which might be mediated by changes in gut microbiota and short chain fatty acid production.