Effects of a Mushroom-Based β-Glucan and Bovine Colostrum Blend on the Gastrointestinal Health and Immune Function of Healthy Adult Dogs.

Mushroom-derived β-glucans and bovine colostrum have potential roles in modulating gut health and immune function, but limited data are available regarding their effects on the gut microbiome, microbial metabolites, and immune responsiveness in adult dogs. Twenty healthy adult beagle dogs (8 females, 12 males; age: 5.6±2.5 yr old; body weight: 9.55±0.92 kg; body condition score: 5.7±0.5) were used in a randomized, blinded, placebo-controlled study using a completely randomized design. After a 3-wk wash-in phase, dogs were assigned to one of two treatment groups (n = 10/group) and fed for 12 wk: placebo consisting of cellulose, rice bran, liver, and natural food coloring or a mushroom complex consisting of mushroom complex consisting of mushroom (turkey tail mushroom, red reishi, and lion's mane) water extracts and bovine colostrum (MC). Each treatment (1.8 g/d) was top dressed on the diet. Fecal samples (characteristics, microbial fermentation metabolites, immunoglobulin A, microbiota) and blood samples (serum chemistry, hematology, immunoglobulins, oxidative stress markers) were collected after the wash-in phase (wk 0) and after 6 and 12 wk. Immune function was evaluated ex vivo by stimulating whole blood cells with toll-like receptor agonists and measuring tumor necrosis factor-alpha production. Data were analyzed using Mixed Models, using baseline data used as a covariate. Statistical significance was set at P < 0.05 and trends were considered at P < 0.10. All dogs remained healthy throughout the study, with fecal characteristics, serum chemistry, hematology, and serum immunoglobulins and oxidative stress markers being unchanged. Dogs fed MC had greater fecal acetate, propionate, and total short-chain fatty acid concentrations than controls. Fecal bacterial alpha and beta diversity metrics remained stable over time. Significant treatment*time interactions were observed for 5 fecal bacterial genera (Atopobiaceae unclassified, Prevotella_9, Lactobacillus, Megamonas, Phascolarctobacterium). Relative abundances of fecal Candidatus_Stoquefichus, Epulopiscium, and Negativibacillus tended to be increased by MC (P < 0.10). The relative abundances of several genera were affected by time. In summary, the mushroom complex was well tolerated and did not adversely affect gut health, immune status, or microbial diversity in healthy dogs. Our results suggest that it may slightly alter gut microbiota populations and microbial fermentation metabolites.