122 - Human-grade Dog Diets Dramatically Shift the Fecal Microbiome of Healthy Adult Dogs

Abstract: Human-grade pet foods have been shown to be highly palatable and digestible, resulting in reduced stool volume, but their impact on the gut microbiome has not been well studied. Therefore, our objective was to compare the fecal characteristics and microbiome of dogs consuming a human-grade or extruded kibble diet. Female beagles (n = 20; BW = 10.25±0.82 kg; age = 3.85±1.84 yr) were used in a completely randomized design. The diets tested were: 1) Chicken and Brown Rice Recipe [extruded; Blue Buffalo (BB)] and 2) Chicken and White Rice [human-grade; Just Food for Dogs (JFFD)]. The study consisted of a 4-week baseline when all dogs were fed BB, and a 12-week treatment phase when dogs were randomized to eat each diet (n=10/group). After the baseline and treatment phases, fresh fecal samples were collected for fecal pH, dry matter (DM), score, and microbiota analysis. Fecal bacterial DNA was extracted and shotgun sequencing was conducted using an Illumina NovaSeq, generating over 1.8 billion reads. Taxonomic and pathway abundances were calculated using MetaPhlan and HUMAnN, respectively. Fecal pH and DM were less (p< 0.05) in dogs fed JFFD than those fed BB, but fecal scores were not affected by diet. PCoA plots based on Bray-Curtis distances of bacterial genera and species showed some shifts over time in dogs fed BB, but much greater shifts in those fed JFFD. JFFD increased (adj p< 0.05) the relative abundances of 4 bacterial genera, 11 bacterial species, 129 KEGG pathways, and 167 Maaslin pathways and decreased (adj p< 0.05) the relative abundances of 16 bacterial genera, 25 bacterial species, 37 KEGG pathways, and 87 Maaslin pathways. In conclusion, the human-grade food tested vastly shifted the fecal microbiome. More research is needed to link taxonomic and gene content shifts to ingredient inclusion, nutrient concentrations, and health outcomes.