Abstract: To investigate the effect of dietary supplementation with oats, tartary buckwheat and foxtail millet on the intestinal histology, microbiota and short-chain fatty acids (SCFAs) in normal rats, 48 male SD rats were randomly and equally divided into four groups: control (fed a standard maintenance diet), oat (fed the maintenance diet containing 22% oats), tartary buckwheat (fed the maintenance diet containing 22% tartary buckwheat) and foxtail millet groups (fed the diet containing 22% foxtail millet). Body mass was recorded weekly. After 12 weeks of feeding, the rats were sacrificed to collect liver tissue, colon tissue and colonic contents. Histopathological characteristics of liver and colon tissues were observed. The intestinal microbiota was analyzed by Illumina NovaSeq high-throughput sequencing technology. SCFAs in colonic contents were determined by liquid chromatography-mass spectrometry. Results indicated that administration of oats increased gut microbiota diversity and showed higher relative abundance of Lactobacillus and Akkermansia than the control group. Tartary buckwheat and foxtail millet increased the relative abundance of Firmicutes, but decreased the abundance of Verrucomicrobia and Bacteroidetes in the gut of normal rats. Oats, tartary buckwheat and foxtail millet decreased the relative abundance of Bacteroides. Oats and foxtail millet could significantly increase the concentrations of acetic acid and total SCFAs (P < 0.05), and foxtail millet could significantly increase the concentrations of propionic acid and isobutyric acid in colonic contents (P < 0.05). In conclusion, oat supplementation has regulatory effects on the gut microbiota in rats, and tartary buckwheat and foxtail millet have similar effects on it. This study provides a scientific basis for the development of cereal-based functional foods.

Key words: oats; tartary buckwheat; foxtail millet; intestinal microbiota; high-throughput sequencing; short chain fatty acid