Kilburn-Kappeler, Logan R, Doerksen, Tyler, Lu, Andrea, Palinski, Rachel M, Lu, Nanyan, and Aldrich, Charles G
Co-products from the ethanol industry, such as distillers dried grains with solubles (DDGS), can provide alternative protein sources for pet food. Corn fermented protein (CFP) is produced using postfermentation technology to split the protein and yeast from fiber prior to drying. This results in a higher protein ingredient compared to DDGS, increasing its appeal for pet food. In addition, the substantial yeast component, at approximately 20% to 25%, may promote gut health through modulation of the microbiome and the production of short-chain fatty acids. Therefore, the objective of this study was to determine the effect of CFP on the fecal microbiome of cats. The 4 experimental diets included a control with no yeast (T1) and diets containing either 3.5% brewer’s dried yeast (T2), 2.5% brewer’s dried yeast plus 17.5% DDGS (T3), or 17.5% CFP (T4). All diets except T1 were formulated to contain 3.5% yeast. Diets were fed to adult cats (n= 11) in an incomplete 4 × 4 replicated Latin square design. Cats were adapted to diet for 9 d followed by a 5-d total fecal collection. During each collection period, fresh fecal samples from each cat were collected and stored at −80 °C until analysis. Fresh fecal samples (n= 44) were analyzed by 16S rRNA gene sequencing. Raw sequences were processed through Mothur (v.1.44.1). Community diversity was evaluated in R (v4.0.3). Relative abundance was analyzed within the 50 most abundant operational taxonomic unitsusing a mixed model of SAS (v9.4, SAS Institute, Inc., Cary, NC). Diet was the fixed effect and cat and period were random effects. Results were considered significant at P< 0.05. Alpha-diversity indices (Observed, Chao1, Shannon, Simpson) and beta-diversity metric (principal coordinate analysis) were similar for all treatments. Predominant phyla were Firmicutes (66%), Bacteroidetes (25%), Actinobacteria (8%), Proteobacteria (0.64%), and Desulfobacteria (0.54%). The relative abundance of Firmicutes and Actinobacteria was lower (P < 0.05) for T3 compared to T4 and T2, respectively. On a more specific phylogenic level, 17 genera resulted in differences (P< 0.05) among dietary treatments. Overall, this data indicates that compared to traditional yeast and distillers dried grains, CFP did not alter the overall diversity of the fecal microbiome of healthy adult cats over a 14-d period.The overall diversity of the fecal microbiome of cats was comparable when fed diets containing either soybean meal, brewer’s dried yeast, a combination of brewer’s dried yeast and distillers dried grains with solubles, or corn fermented protein. However, the relative abundance of taxonomic classifications shifted based on dietary substrate available for microbial fermentation.Specific components of yeast may affect gut microbiota and health. Corn fermented protein (CFP) is a co-product from ethanol production which contains approximately 20% to 25% yeast. In this work, 11 cats were fed diets containing no yeast (T1) and either 3.5% brewer’s dried yeast (T2), 2.5% brewer’s dried yeast plus 17.5% distillers dried grains with solubles (T3), or 17.5% CFP (T4). Cats were fed each dietary treatment for 14 d with a 9-d adaptation phase followed by a 5-d total fecal collection. Fresh fecal samples were analyzed by 16S rRNA gene sequencing. Beta and alpha diversity were comparable for cats fed dietary treatments. The relative abundance of the Firmicutes and Actinobacteria phyla was lower for T3 compared to T4 and T2, respectively. When compared on a more specific phylogenic level, 17 genera out of the 50 most abundant OTU resulted in significant differences among dietary treatments. This data indicates that CFP did not alter the overall diversity of the fecal microbiome of healthy adult cats over a 14-d period. The shifts in relative abundance of taxa appeared to be influenced by the type of dietary substrate available for microbial fermentation.