Effects of Dietary Yeast Culture Product Supplementation on Fecal Microbial Communities of Adult Healthy Dogs

Prebiotics, defined as dietary fibers that can benefit to the host by selectively stimulating the growth and activity of beneficial intestinal bacteria, have gained increased attention in companion animal nutrition. However, limited information is available on prebiotic supplementation and canine GI microbiota using high-throughput molecular techniques. Thus, the aim of this study was to evaluate the effects of increasing dietary concentrations of a yeast culture product (YCP) on fecal microbiota of adult healthy dogs. Eighteen dogs (15.8 ± 7.37 kg mean BW; 3.7 ± 1.62 yr mean age) were randomly assigned onto 1 of 3 treatments; control diet (CO), CO supplemented 0.3% YCP (YCP-0.3) and CO supplemented 0.6% YCP (YCP-0.6). The experimental period consisted of 21-d of diet adaptation, followed by 3-d of fresh fecal collection. Three fecal samples were collected from each dog within 15 minutes of defecation and stored at -80^oC. Fecal genomic DNA was extracted using Mo-Bio PowerSoil kits. The V4 region of the 16S rRNA gene was amplified and sequenced using Fluidigm specific primers and MiSeq (v3 reagents). High quality sequences were analyzd using QIIME 1.9.1 and mixed procedure of SAS, with P ≤ 0.05 considered as statistically significant, whereas a P ≤ 0.10 was considered as trend. A total of 917,433 reads were obtained. An even sampling depth of sequences per sample (16,300 reads) was used for assessing alpha- and beta-diversity. YCP supplementation did not affect fecal microbial alpha- and beta-diversities. Firmicutes and Fusobacteria made up about 85-88% of bacterial sequences, with Bacteroidetes, Proteobacteria, Actinobacteria and Deferribacteres contributing to only about 8-12%, 1-3%, 0.1 - 2% and < 0.02% of sequences, respectively. The predominant fecal bacterial genera were Clostridium (18-15%), Fusobacterium (16-25%) and Blautia (7-11%). Supplementation of YCP-0.6 tended to increase the relative abundance of Collinsella and Slackia , while tended to decrease (P < 0.10) fecal Coprobacillus. In conclusion, supplementation of 0.6% of YCP resulted in modest changes in fecal microbial communities of healthy adult dogs. Further studies should evaluate higher doses of YCP supplementation and its effects on fecalmicrobiota and gut health of dogs suffering from gastrointestinal disorders.