Novel Dietary Fiber Blend Alters Metabolism of Gastrointestinal Microbiome to Improve Digestive Health and Produce Beneficial Postbiotics in Adult Dogs

Abstract

The canine gastrointestinal (GI) microbiome is capable of fermenting a variety of plant fibers. Addition of dietary fibers from select plant sources may promote improvements in canine GI health. A novel fiber blend was prepared with pecan shells, flaxseed, beet pulp, citrus pulp & crushed cranberries.16 adult dogs were assigned to group 1 & fed a control food (CF1): hydrolyzed protein formula without the novel fiber blend during a 3 week pre-feed, then switched to the test food (TF1): hydrolyzed protein formula with the novel fiber blend for 3 weeks (CF1: 3770 kcal/kg, 0.3 g total dietary fiber (TDF), 0.1 g soluble fiber (SF), & 0.3 g insoluble fiber (INSF), per 100 kcal; TF1: 3646 kcal/kg, 2.7 g TDF, 0.4 g SF, 2.2 g INSF per 100 kcal). 16 dogs were assigned to group 2 & fed a control food (CF2): high grain formula without the novel fiber blend during a 3 week pre-feed, then switched to the test food (TF2): high grain formula with the novel fiber blend for 3 weeks (CF2: 3613 kcal/kg, 1.4 g TDF, 0.3 g SF, & 1.1 g INSF, per 100 kcal; TF2: 3580 kcal/kg, 2.0 g TDF, 0.1 g SF, 1.8 g INSF per 100 kcal). All foods were nutritionally complete & balanced dry foods & met 2019 AAFCO guidelines for adult dogs. All dogs were fed to maintain body weight. Stool samples were collected on pre-feed day 19±2& on day 19±2 of feeding each test food, & were scored on a 5 point scale (1= liquid stool to 5= firm stool), homogenized, & frozen at −70C within 1 hour of defecation. Untargeted metabolomics analysis was performed by a commercial lab. Fecal proximate & short chain fatty acid (SCFA) analyses were conducted using certified official compendial methods. All study protocols were reviewed & approved by the Institutional Animal Care & Use Committee, Hill's Pet Nutrition, Inc. A linear mixed model was used to analyze fecal moisture, pH, SCFAs, & metabolites. Results significant at p<0.05 are reported. Dogs in both groups had improved stool scores, decreased fecal pH, & increased levels of fecal metabolites derived from fiber, including saccharolytic products arabinose & ribulose/xylulose, phenolic compounds (apigenin, diosmetin, eriodictyol, hesperidin, narirutin & tangeritin), & microbially-produced postbiotics (4-hydroxycinnamate, enterodiol, hesperetin, naringenin, ponciretin, & secoisolariciresinol) when fed TF1 & TF2 vs CF1 & CF2, respectively. Dogs in group 1 had decreased fecal moisture & increased straight SCFAs (acetic acid, butyric acid, & propionic acid) when fed TF1 vs CF1. Dogs in group 2 had decreased fecal levels of putrefactive metabolites, including branched SCFAs (isobutyric, 2-methylbutyric, & isovaleric acids) & polyamines (putrescine, spermidine, & spermine) when fed TF2 vs CF2. Test foods containing this novel fiber blend improved stool parameters, increased fecal saccharolytic & fermentative metabolites, increased vital energy sources for colonocytes, decreased putrefactive end products, & increased antioxidant & anti-inflammatory plant-derived polyphenol postbiotics to the lower GI tract of adult dogs.