Fructooligosaccharides and Lactobacillus acidophilus modify gut microbial populations, total tract nutrient digestibilities and fecal protein catabolite concentrations in healthy adult dogs

The objective of this research was to determine whether fructooligosaccharides (FOS) and (or) Lactobacillus acidophilus (LAC) affected concentrations of gut microbial populations, fermentative end products and nutrient digestibilities in healthy adult dogs. Two experiments were performed using 40 adult dogs (20 dogs/experiment). Dogs in each experiment were randomly assigned to one of 4 treatments. Twice daily, treatments were given orally via gelatin capsules: 1) 2 g sucrose + 80 mg cellulose; 2) 2 g FOS + 80 mg cellulose; 3) 2 g sucrose + 1 × 10⁹ colony forming units (cfu) LAC; or 4) 2 g FOS + 1 × 10⁹ cfu LAC. Data were analyzed by the General Linear Models procedure of SAS. In Experiment 1, FOS resulted in lower (P = 0.08) Clostridium perfringens and greater fecal butyrate (P = 0.06) and lactate (P < 0.05) concentrations. In Experiment 2, FOS supplementation increased (P < 0.05) bifidobacteria, increased lactobacilli (P = 0.08), increased fecal lactate (P = 0.06) and butyrate (P < 0.05), and decreased (P < 0.05) fecal ammonia, isobutyrate, isovalerate and total branched-chain fatty acid concentrations. Dogs fed LAC had the highest fecal concentrations of hydrogen sulfide and methanethiol in Experiment 1 and dimethyl sulfide in Experiment 2, whereas dogs fed FOS had the lowest concentrations of these compounds. Overall, FOS appeared to enhance indices of gut health by positively altering gut microbial ecology and fecal protein catabolites, whereas LAC was more effective when fed in combination with FOS rather than fed alone.