摘要Indole-3-propionic acid(IPA)is a metabolite of tryptophan produced by gut bacterial catabolism that has a variety of functions,including anti-inflammatory,free radical scavenging,and regulation of glucose metabolism.The present study evaluated the effects of dietary IPA supplementation on early muscle development in piglets.Twelve healthy Landrace × Rongchang piglets at 30 d of age were randomly divided into control(CON group,10.78±0.040 kg)and 0.01％IPA(IPA group,10.80±0.062 kg)for 50 d.The results showed that IPA increased the proportion of glycolytic myofibers significantly in muscle(P=0.002).Supplementation with IPA increased pyruvate kinase(PK)activity(P=0.025)and gene expression of myosin heavy chain 4(MYH4)in muscle(P＜0.001),and decreased the gene expression of MYH7 and MYH2(P＜0.01)and mitochondrial respiratory chain complexes(P＜0.01).Supplementation with IPA enhanced insulin sensitivity and activated phosphatidylinositol 3-kinase(PI3K)-protein kinase B(Akt)-mammalian target of rapamycin(mTOR)pathway in vivo and acceler-ated differentiation of C2C12 cells in vitro.In addition,IPA affected gut microbiota by increasing the Firmicutes-to-Bacteroidetes ratio and significantly reduced the concentration of kynurenine and melatonin(P＜0.05).In conclusion,IPA increased glycolytic myofibers and promoted muscle growth by regulating the homeostasis of glucose metabolism mediated by PI3K-mTOR signaling and the gut microbiota in piglets.