Effects of Dietary Ferulic Acid on the Intestinal Microbiota and the Associated Changes on the Growth Performance, Serum Cytokine Profile, and Intestinal Morphology in Ducks.

The present study investigated the effects of ferulic acid (FA) on the growth performance, serum cytokine profile, intestinal morphology, and intestinal microbiota in ducks at the growing stage. 300 female ducks at 28 days of age with similar body weights were randomly divided into five groups. Each group contained six replicates of 10 birds. The dietary treatments were corn-soybean-based diet supplemented with FA at the concentrations of 0 (control), 100, 200, 400, and 800 mg/kg diet. The results demonstrated that dietary FA at the levels of 200, 400, and 800 mg/kg increased the average daily gain ( = 0.01), 400 and 800 mg/kg FA increased the final body weight ( = 0.02), 100, 200, and 800 mg/kg FA increased the serum glutathione ( = 0.01), and 100, 400, and 800 mg/kg FA increased the glutathione peroxidase activities in birds ( < 0.01). Additionally, 200, 400, and 800 mg/kg dietary FA lowered the serum levels of interleukin-2 ( = 0.02) and interleukin-6 ( = 0.04). Moreover, the morphometric study of the intestines indicated that 400 mg/kg FA decreased the crypt depth in jejunum ( = 0.01) and caecum ( = 0.04), and increased the ratio of villus height to crypt depth in jejunum ( = 0.02). Significant linear and/or quadratic relationships were found between FA concentration and the measured parameters. 16S rRNA sequencing revealed that dietary FA increased the populations of genera , , RF39, and in the cecum ( < 0.05), whereas decreased the populations of and UCG-002 ( < 0.05). The Spearman correlation analysis indicated that phylum were negatively, but order , and family were positively related to the parameters of the growth performance. Phylum , class and family were negatively associated with the parameters of the antioxidative capability. And phylum , , and , class , family , and genus were positively associated with the parameters of the immunological capability. Thus, it was concluded that the supplementations of 400 mg/kg FA in diet was able to improve the growth performance, antioxidative and immunological capabilities, intestinal morphology, and modulated the gut microbial construction of ducks at the growing stage.