Dietary areca nut extract supplementation modulates the growth performance and immunity of Jiaji ducks (Cairina moschata)

Areca nut extract (ANE) has a variety of pharmacological effects on animals. Here, we investigated the influence of ANE on the slaughter performance and immune function of Jiaji ducks. One hundred and fifty 42-day-old healthy Jiaji ducks were randomly divided into 2 groups (5 replicates of 15 ducks each), named DCK group (control) and DNT group (treatment), respectively. Ducks in the DCK group were fed a basal diet and ducks in the DNT group were fed a basal food supplemented with 0.08 g ANE per kg of basal diet. Additionally, using proteomics, untargeted metabolomics, and metagenomics, we analyzed the impact of ANE on the protein profile of the spleen, the composition of plasma metabolites, and the structure of the cecal microbiota. The results showed that the dietary inclusion of ANE significantly increased the slaughter rate of Jiaji ducks. Proteomic analysis revealed 78 differentially expressed proteins in the spleens of ANE-treated birds, including 54 proteins up-regulated and 24 proteins down-regulated in the DNT group, mainly enriched in cell adhesion molecules and glutathione metabolic pathways. Untargeted metabolomic analysis revealed that 117 serum metabolites were differentially regulated between the ANE and DCK groups; meanwhile, KEGG pathway analysis indicated that these metabolites were mainly involved in arachidonic acid metabolism, phospholipase D signaling pathway and eicosanoids. Furthermore, a metagenomic analysis showed that the genus Methanobrevibacter was significantly downregulated in the ANE supplementation group. Combined, the results of the metagenomic and metabolomic analyses showed that the relative abundance of Prevotella was significantly lower in the ANE group than in the DCK group and that Prevotella was negatively correlated with the levels of the anti-inflammatory compound hydrocinnamic acid and the lipid metabolism regulator ganoderic acid A. This study provides a reference for the application of ANE as a supplement in the diet of Jiaji ducks.