The objective of this study was to evaluate health outcomes resulting from dietary supplementation of novel, low-digestible carbohydrates in the cecum and colon of Sprague-Dawley rats randomly assigned to one of four treatment groups for 21 days: 5% cellulose (Control), Pectin, soluble fiber dextrin (SFD), or soluble corn fiber (SCF). Rats fed Pectin had a higher average daily food intake, but no differences in final body weights or rates of weight gain among treatments were observed. No differences were observed in total short-chain fatty acid (SCFA) or branched-chain fatty acid (BCFA) concentrations in the cecum and colon of rats fed either SFD or SCF. The SFD and SCF treatments increased cecal propionate and decreased butyrate concentrations compared to Control or Pectin. Pectin resulted in increased BCFA in the cecum and colon. Supplementation of SFD and SCF had no effect on cecal microbial populations compared to Control. Consumption of SFD and SCF increased total and empty cecal weight but not colon weight. Gut histomorphology was positively affected by SFD and SCF. Increased crypt depth, goblet cell numbers, and acidic mucin were observed in both the cecum and colon of rats supplemented with SFD, SCF, and Pectin. These novel, low-digestible carbohydrates appear to be beneficial in modulating indices of hindgut morphology when supplemented in the diet of the rat.

The increasing demand for functional ingredients has drawn attention to yeast and yeast-derived ingredients in pet foods. This experiment aimed to evaluate the in vitro fermentation characteristics of common dietary fibers using fecal inoculum from dogs fed either a control diet (CTRL) or a diet supplemented with dried brewers yeast at 1.5% inclusion (BY). Sixteen healthy adult dogs were acclimated for 7 d and then randomly assigned to the two treatments (n = 8/group) for 21 d. Fecal samples collected at the end of the treatment period, were preserved in 20% glycerol and later used as inoculum for in vitro fermentation of beet pulp, pectin, and cellulose over 0, 6, 12, or 18 h. Fermentation patterns differed among fiber substrates. Pectin was highly fermentable, beet pulp showed moderate fermentation, and cellulose was minimally fermented, as indicated by SCFA production and pH changes. Within each fiber, BY inocula produced more SCFA and a lower pH than CTRL after 18 h, with the largest SCFA differences observed in beet pulp tubes (3549 vs. 2980 μmole/g) and the greatest pH differences in pectin tubes (−1.66 vs. –1.54). Microbiota analysis revealed increased relative abundances of SCFA-producing genera, along with reduced relative abundances of Fusobacterium, Streptococcus, and Sutterella. Overall, dried brewers yeast supplementation can influence canine gastrointestinal microbiota composition and fermentative activity in vitro.