As a fermentable milk drink, kefir may affect gastrointestinal microbiota, but such products are poorly studied in companion animals. Our objective was to determine how commercial or traditional kefir feeding impacted the in vitro fermentation characteristics of fibers common in pet foods. Healthy adult dogs consumed reduced-fat milk (control; CNTL), starter kefir (S-Kefir), or grain kefir (G-Kefir) for 14 d, with fresh fecal samples collected and used for an in vitro fermentation experiment. Feces-inoculated tubes contained a semi-defined medium and one of the following purified fiber sources: pectin, cellulose, beet pulp, or chicory pulp. Tubes were incubated for up to 18 h. Effects of treatment, time, and treatment*time interactions within the fiber source were analyzed. pH change was greater in S-Kefir or G-Kefir tubes than CNTL. With pectin and beet pulp, S-Kefir tubes had greater increases in acetate, propionate, and total short-chain fatty acids than G-Kefir or CNTL tubes. Increases in butyrate were greater in G-Kefir tubes than S-Kefir or CNTL tubes, and greater in S-Kefir than CNTL tubes. Bacterial alpha diversity, beta diversity, and relative abundances of several bacterial genera were affected by inoculum source. These data suggest that kefir consumption changes the abundance and activity of canine fecal microbiota.

Read the full article in the Journal of Animal Science.