Influence of some potential prebiotics and fibre-rich foodstuffs on composition and activity of canine intestinal microbiota

The aim of the present study was to evaluate the effect on the composition and activity of the canine intestinal microbiota of different sources of soluble fibre that are among the most widely used by the pet food industry, and some prebiotic substances that might be considered as potential ingredients for dog diets. In vitro, there were 14 treatments: Control diet; Lactitol; Beneo P95 (FOS from partially hydrolyzed inulin from chicory); Fibrulose F97 (FOS from chicory); Fibruline XL (inulin from chicory); Pectin Classic AU202 (pectins from apple); Pectin Classic CU201 (pectins from citrus fruit); Beneo GR (inulin from chicory); Gluconic acid; Dried chicory; Dried beet pulp; Exafine 500 (pea hull fibre); Psyllogel (850 g/kg Psyllium fibre); Benefibra (partially hydrolyzed guar gum). Substrates were added at 1 g/L (treatments 2 through 9) or 4 g/L (treatments 10 through 14) to canine faecal cultures for a 24 h incubation. In view of the different beneficial properties that they showed during the in vitro trial, Lactitol and Pectin Classic CU201 were selected to be tested in a feeding study with 16 privately owned dogs. Dogs were divided into two treatment groups of eight animals each; all dogs were fed the same commercial dry diet (the same one used for the in vitro study) and received 1) lactitol or 2) Pectin Classic CU201 at 10 g/kg of diet for 30 d. Faecal samples were collected at 0, 20, and 30 d after the start of the trial and 10 d (Day 40) after prebiotic withdrawal. In vitro, compared with the control, gas production and maximum rate of gas production were increased (P<0.01) by most substrates. Pectin Classic CU201 was the only substrate that resulted (P<0.01) in a lower ammonia concentration than the control both after 6 and 24 h of fermentation. Compared with the control, lactitol, FOS, Psyllogel and Benefibra increased propionic acid and reduced the acetic + n-butyric to propionic acid ratio (P<0.01). Pectins resulted in higher acetic and n-butyric acid levels than the control (P<0.01). Compared with the control, coliforms were reduced (P<0.01) by lactitol both in vitro and in vivo (-2 log units). In vitro, several substrates resulted in higher counts of lactobacilli and enterococci than the control (P<0.01). In vivo, compared with faecal counts at trial start, lactobacilli and enterococci were not affected (P>0.05) by treatment, whereas prebiotics resulted in reduced concentrations of coliforms and C. perfringens (P<0.05). This study produced evidence that different prebiotic substances and fibre rich foodstuffs exert different effects on the composition and activity of canine intestinal microbiota.