Comparison of fermentation of selected fructooligosaccharides and other fiber substrates by canine colonic microflora

To compare fermentation characteristics of fructooligosaccharides (FOS) and other fiber substrates that are commonly found in canine diets. Fecal samples from 3 adult dogs. The ability of fiber substrates to be used in microbial fermentation reactions was assessed by use of an in vitro fermentation system. Dogs were fed a commercially available food, and feces were collected for use as the microbial inoculum. Substrates used were beet pulp, cellulose, soy fiber, mannanoligosaccharides (MOS), FOS, and 4 inulin products (inulin 1, 2, 3, and 4). Each substrate was incubated anaerobically with fecal inoculum and growth media for 6, 12, and 24 hours, and production of short-chain fatty acids (SCFA) was measured. Total production of SCFA was higher for fermentation of the 4 inulin products and FOS, whereas fermentation of beet pulp, MOS, and soy fiber resulted in moderate concentrations of SCFA. Fermentation of cellulose produced the lowest concentrations of total SCFA without detection of butyrate or lactate. Butyrate production was greatest for fermentation of the 4 inulin products and FOS. Total lactate production was greatest for FOS and inulin 4. As expected, production of SCFA increased for all substrates as fermentation time increased. Canine fecal microflora ferment FOS-containing substrates in a similar manner, with little fermentation of cellulose-based carbohydrates. Furthermore, results of an in vitro fermentation system indicate that fiber type affects the metabolic activity of microorganisms, thus influencing the amount and nature of the end products of fermentation.