Abstract: Objective: To study the effects of four common minor cereals in China (buckwheat, oat, proso millet and millet) on the intestinal microbiota and short chain fatty acids in rats. Methods: Fifty seven-week-old male SD rats (weighing (302.10 ± 9.58) g) were randomly divided into five groups: control, oat, buckwheat, proso millet and millet. The control group was fed a basal diet, while the remaining groups were fed 50% of the basal diet and 50% of the corresponding cereals for six weeks. During the experimental period, the feed intake and body mass of rats were measured every week. At the end of the experimental period, the feces of rats were collected to determine the water content. The cecum and colon were weighed, and the pH and short-chain fatty acid content of cecum and colon were determined. The composition and distribution of bacterial flora in the ileum, cecum and colon were measured. Results: The fecal moisture contents of rats fed buckwheat, oat and millet (25.76%, 24.64% and 22.45%, respectively) were significantly higher than that of the control group (12.06%). The pH values of cecal contents (6.21–6.91) and colonic contents (6.01–6.15) of rats fed minor cereals were significantly lower than those of the control group (7.28 and 6.93, respectively). The total amounts of short-chain fatty acids in cecal contents (23.78–37.89 μmol/g) and colonic contents (80.82–153.46 μmol/g) were significantly greater than those in the control group (14.99 and 46.15 μmol/g, respectively), with the highest levels being observed in the buckwheat group (37.89 and 153.46 μmol/g, respectively). In ileum, cecum and colon contents of rats, Firmicutes was dominant. The ratio of Firmicutes to Bacteroides in cecum and colon contents was lower than that in ileum contents. The ratio of Firmicutes to Bacteroides in cecum contents was lower in the four cereal groups compared with the control group. The ratio of Firmicutes to Bacteroidetes in ileum, cecum and colon contents was 39.2%, 38.8% and 24.5% lower in the buckwheat group than that in control group, respectively. Conclusion: Minor cereals especially buckwheat play an important role in regulating the pH, short-chain fatty acid contents and microbiota of intestinal contents in rats. Accordingly, moderate intake of minor cereals should be ensured in the daily diet.

Key words: minor cereals; intestine; microbiota composition; short chain fatty acids; rats