DIETARY FIBER FOR DOGS .4. IN-VITRO FERMENTATION OF SELECTED FIBER SOURCES BY DOG FECAL INOCULUM AND IN-VIVO DIGESTION AND METABOLISM OF FIBER-SUPPLEMENTED DIETS

Two experiments were conducted to evaluate single sources and blends o f dietary fiber in dog food. In Exp. 1, 14 fibrous substrates were fer mented in vitro using dog feces as the source of inoculum. Organic mat ter disappearance was lowest (P < .05; < 10%) for Solka Floc(R) and oa t fiber and greatest (P < .05; > 80%) for fructooligosaccharides (FOS) and lactulose. Solka Floc, oat fiber, gum karaya, and xanthan gum pro duced the least (P < .05; < 1 mmol/g of substrate OM) total short-chai n fatty acids (SCFA). Lactulose, citrus pectin, and guar gum produced the greatest (P < .05; > 6.8 mmol/g of substrate OM) total SCFA. In Ex p. 2, six diets were formulated based on results obtained in Exp. 1. T reatments included 1) beet pulp (BP), 2) Solka Flee (SF), 3) citrus pu lp (CP), 4) stool blend (SE), 5) SCFA blend (SC), and 6) combination b lend (CB). Digestibility of DM and total dietary fiber (TDF) was great est (P < .05; 87.3 and 60.8%, respectively) for dogs consuming the SC diet. Feces from dogs fed SC were scored as more unformed and liquid i n consistency than feces from dogs fed the other diets. Dogs consuming the SF and SE diets had the lowest (P < .05; 11.0 and 4.1%, respectiv ely) TDF digestibilities. Organic matter disappearance values derived from substrates fermented in vitro reasonably predicted the fiber dige stibility of diets fed to dogs. Moderately fermentable dietary fiber s ources, such as BP, promote excellent stool characteristics without co mpromising nutrient digestibility, and may promote gastrointestinal tr act health by optimizing SCFA production.