N-Carbamylglutamate Promotes Growth and Immunity in Danzhou Chickens via Gut Microbiota-Metabolite Interactions Involving Sphingolipid and mTOR Pathways

This study evaluated the effects of dietary supplementation with N-Carbamylglutamate (NCG) on growth performance, immune function, intestinal metabolites, and microbiota in Danzhou chickens. In a 35-day feeding trial, a total of 480 one-day-old female chicks were randomly assigned to a control group (basal diet) and three experimental groups supplemented with 400, 800, or 1200 mg/kg NCG, with 120 chicks in each group (n = 120). The results demonstrated that NCG, particularly at 400 mg/kg, significantly improved growth parameters, including average daily gain and feed conversion ratio, while enhancing immune function by increasing serum levels of immunoglobulins (IgA, IgY) and malate dehydrogenase (p < 0.05). Metabolomic analysis revealed that NCG modulated key pathways such as sphingolipid metabolism and mTOR signaling pathway, leading to significant changes in metabolites including L-arginine, ceramide, and docosahexaenoic acid (p < 0.05). 16S rDNA sequencing indicated that NCG induced structural shifts in the gut microbiota, primarily affecting Bacteroidota and Firmicutes, with several bacterial genera showing strong correlations with the observed metabolic changes (p < 0.05). Mechanistically, NCG promotes growth by facilitating arginine synthesis via the urea cycle and activating the mTOR signaling pathway, while its regulation of sphingolipid metabolism enhances immunomodulatory capacity. In conclusion, NCG enhances feed efficiency and immune competence by orchestrating the gut microbiota-metabolite network, demonstrating its potential for poultry production.