Low-level fructan supplementation of dogs enhances nutrient digestion and modifies stool metabolite concentrations, but does not alter fecal microbiota populations.

Five ileal-cannulated adult dogs were utilized in a 5 x 5 Latin square design to determine the effects of fructan type and concentration on nutrient digestibility, stool metabolite concentrations, and fecal microbiota. Five diets were evaluated that contained cellulose alone or with inulin or short-chain fructooligosaccharides (scFOS) each at 0.2 or 0.4% of the diet. Dogs were fed 175 g of their assigned diet twice daily. Chromic oxide served as a digestibility marker. Nutrient digestibility; ileal and fecal pH and ammonia concentrations; ileal IgA concentrations; and fecal short- and branched-chain fatty acid concentrations, microbiota, and concentrations of phenol, indole, and biogenic amines were measured. No differences were observed in ileal pH or ammonia or fecal concentrations of indole or valerate. Ileal DM, OM, and CP digestibility coefficients; total tract DM and OM digestibility coefficients; and fecal concentrations of phenylethylamine increased linearly (P < 0.05), and fecal concentrations of phenol decreased linearly (P < 0.05) with inulin supplementation. Fecal concentrations of acetate, propionate, and total short-chain fatty acids decreased quadratically (P < 0.05) with inulin supplementation. Ileal DM, OM, and CP digestibility coefficients increased linearly (P < 0.05), and fecal phenol concentration decreased linearly (P < 0.05) with scFOS supplementation. Total tract DM and OM digestibility coefficients as well as fecal butyrate and isobutyrate concentrations increased quadratically (P < 0.05) with scFOS supplementation. Although a greater level of inclusion is needed to modify gut microbiota populations, low-level inclusion of inulin or scFOS is effective in modifying key nutritional outcomes in the dog.