Restricted Feeding and Weight Loss Change Fecal Metabolite Concentrations and Microbiota Populations of Overweight Cats

Abstract Feline obesity negatively influences many metabolic processes, health outcomes, and the individual well-being of cats, but little research evaluates the modification in gastrointestinal microbiota in an overweight state. The use of specially formulated diets and restricted feeding, resulting in subsequent body weight (BW) loss, may be used to improve health and modify gastrointestinal microbiota of overweight cats. This study aimed to identify and determine the effects of restricted feeding and BW loss on fecal metabolite concentrations and microbiota populations of overweight cats. All procedures were approved by the University of Illinois IACUC before experimentation. Twenty-two overweight adult spayed female and neutered male cats [BW = 5.70 ± 1.0 kg; BCS = 7.68±0.6; age = 4 ± 0.4 yr] were used in a 24-wk BW loss study. A control diet (OR) was fed during a 4-wk baseline to identify intake needed to maintain BW. After baseline (wk 0), cats were allotted to OR or a BW loss diet (FT) and fed to lose ~1.0% BW/wk. Fecal samples were collected at baseline (wk 0), and weeks 4, 8, 12, 16, 20, and 24 for microbiota and metabolite analyses. Fecal microbiota data were analyzed and evaluated using QIIME2 and Mixed Models procedure of SAS, with P < 0.05 considered significant. Change from baseline fecal acetate, propionate, butyrate, total short-chain fatty acid, isobutyrate, valerate, phenol, indole, and total phenol and indole concentrations were reduced (P < 0.05) with restricted feeding and BW loss. Change from baseline fecal scores and valerate concentrations were also affected by diet, with greater (P < 0.05) reductions occurring in cats fed OR than those fed FT. Change from baseline fecal pH was also greater (P = 0.05) in cats fed OR than those fed FT. Fecal bacterial alpha diversity was not affected by diet or restricted feeding and BW loss. However, fecal bacterial beta diversity, assessed by weighted and unweighted UniFrac distances and presented as principal coordinate plots, showed separation between dietary groups, with some significant clustering as a result of restricted feeding and weight loss. The relative abundances of a single fecal bacterial phylum and 5 fecal bacterial genera were impacted by restricted feeding and weight loss. Diet had a greater effect, with 3 fecal bacterial phyla and 19 fecal bacterial genera being different (P < 0.05) between dietary treatment groups. Our data demonstrate that restricted feeding of specially formulated diets, and subsequent BW loss, modifies the fecal metabolite profiles and microbiota populations of overweight cats. The mechanisms by which these changes may affect feline gastrointestinal health and metabolism requires further study.