Different starch sources result in distinct responses to diets digestibility, fecal microbiota and fermentative metabolites, and postprandial glycemic response in dogs

The study evaluated the effects of different starch sources on the coefficients of total tract apparent digestibility (CTTAD) of macronutrients, metabolizable energy (ME), intestinal fermentative metabolites, fecal microbiota, and postprandial glycemic response in dogs. Seven diets containing corn, brown rice, sorghum, potato starch, sweet potato flour, chickpea, and pea flour were evaluated. Fourteen adult Beagle dogs were randomly distributed in blocks (periods) and were fed the experimental diets for 15 days during three periods, totaling 6 repetitions. In general, diets with brown rice and pea had higher CTTAD of nutrients, followed by diets containing sorghum, chickpea, and potato. The diet containing sweet potato had the lowest CTTAD of nutrients. Diets containing corn and brown rice presented the highest ME content. Dogs fed the chickpea diet had lower fecal pH, ammonia concentration, and dry matter content (P < 0.05). Generally, higher fecal concentrations of short-chain fatty acids were observed in dogs fed the sweet potato and chickpea diets compared to the potato and brown rice diets (P < 0.05). Pulse-based diets resulted in a higher abundance of Bacteroides plebeius, Prevotella copri, Blautia, and Turicibacter in feces (P < 0.05). A higher abundance of Faecalibacterium prausnitzii and Blautia was observed in the feces of dogs fed the sweet potato diet (P < 0.05). Blood samples collected from dogs fed corn and potato diets indicated a greater increase in glycemic peak concentration and maximum glycemia than the other starch sources (P < 0.05). The period until the glycemic peak was longer for diets containing sorghum and chickpea (P < 0.05). The results obtained in this study showed that sweet potato and pulses improve indicators of gastrointestinal functionality, and help controlling the postprandial glycemic response in dogs.