Dietary curcumin supplementation enhances growth performance and anti-inflammatory functions by modulating gut microbiota, microbiota-derived metabolites, and expression of inflammation-related genes in broilers

Curcumin (CUR) is a natural polyphenolic substance that has been widely used since ancient times for its multiple beneficial functions. However, whether CUR affects the growth performance of broilers by altering gut microbiota and metabolite and the underlying mechanism are largely unknown. This study was conducted to evaluate the effect of dietary CUR supplementation on growth performance, anti-inflammatory function, intestinal morphology and barrier, cecum microbiota, and metabolite profile of broilers. Sixty-one-day-old male broilers were randomly divided into the control group (CON, fed a control diet) and the CUR group (fed a control diet supplemented with 200 mg/kg CUR) after 2 d of adaptation. Results showed that after feeding to 52-d-old, compared with CON broilers, the CUR broilers showed improved feed utilization efficiency and growth performance. Furthermore, the CUR broilers showed an improved intestinal morphology, which was demonstrated by a lower crypt depth in the jejunum. The 16S rRNA gene sequencing and non-targeted metabonomics (LC-MS/MS) analysis results showed that the cecum microbiota ecology and function were significantly improved, and the abundance of beneficial flora and metabolites were increased, while the harmful bacteria and metabolites were significantly decreased. In addition, RT-qPCR results showed that CUR significantly reduced inflammatory responses, promoted the formation of the mucosal barrier and enhanced digestion, absorption, and transport of lipids and glucose-related gene expression in the intestine. These above findings demonstrated that dietary CUR supplementation improved growth performance, intestinal morphology, and anti-inflammatory functions, mainly by manipulating cecum microbiota and microbiota-derived metabolites, which provides a credible explanation for the growth-promoting effect and anti-inflammatory functions of CUR and aids our understanding of the mechanisms underlying.