Effects of dietary N‐carbamylglutamate supplementation on the modulation of microbiota and Th17/Treg balance‐related immune signaling after lipopolysaccharide challenge

Abstract Background This study aimed to evaluate the effects of N ‐carbamylglutamate (NCG) on piglets' growth performance and immune response, and to unravel the mechanisms of such effects. In a 2 × 2 factorial design including diet (with or without NCG) and immunological challenge (saline or lipopolysaccharide (LPS)), 24 piglets were randomly distributed into four groups. After being fed a basic diet or a NCG‐supplemented diet for 21 days, piglets were administered LPS or saline intraperitoneally. Results The results showed that NCG increased the average daily gain and average daily feed intake, and the feed conversion ratio of piglets, and alleviated the adverse effects of LPS stimulation on intestinal morphology. At the phylum level, NCG reversed the increase in the abundance of Firmicutes and the reduction in that of Actinomycete caused by LPS stimulation. At the genus level, NCG increased the abundance of Lactobacillus , Blautia , norank_Butyricicoccaceae , Subdoligranulum , and Ruminococcus_gauvreauii_group , and LPS decreased the abundance of Escherichia‐Shigella and Ruminococcus_gauvreauii_group . The short‐chain fatty acid content was increased by NCG, but LPS reduced its content. N ‐Carbamylglutamate also inhibited significantly the LPS‐induced increase in the relative expression of signal transducer and activator of transcription ( STAT ) 3, related orphan receptor (RAR) c, and pro‐inflammatory cytokines, and the decrease in the relative expression of STAT5, forkhead box P3, IL‐10 and transforming growth factor beta 1 mRNA. A significant correlation was found between intestinal microbiota and inflammatory cytokines and short‐chain fatty acids. Conclusion N ‐Carbamylglutamate can improve piglets' growth performance. It can also attenuate LPS‐induced intestinal inflammation by modulating microbiota and Th17/Treg balance‐related immune signaling pathways. © 2023 Society of Chemical Industry.