PSVIII-15 - Saccharomyces cerevisiae fermentation product influences indicators of gut health and function in healthy adult cats

Abstract: Compared to other species, the gastrointestinal influences of dietary Saccharomyces cerevisiae fermentation product (SCFP) in cats are not well-characterized. In this study, SCFP (TruMune, Cargill, Inc.) was added to an extruded cat food to explore gut-related outcomes in healthy adult cats. Sixty-three cats (mean age=6.3±2.8 y; mean BW=4.4±0.1 kg) were used in a randomized complete block design to evaluate a base diet without SCFP (CON) or supplemented with 150 mg/kg BW SCFP (TRUL) or 300 mg/kg BW SCFP (TRUH). All cats were fed CON during a 21-d adaptation period and subsequently fed their respective diet from d0 to d42. Fecal samples were collected at d0, d21 and d42 for analysis of fecal characteristics, fermentation end-products and shotgun metagenomics. A 5-d total fecal collection was performed from d35 to d39 for analysis of apparent nutrient digestibility. Data were analyzed using R v.4.1.2. Non-metagenomic data were analyzed using linear and generalized linear mixed models with lme4 and emmeans packages and metagenomic data were analyzed using phyloseq, vegan, lme4, LinDA and emmeans packages. Differences P < 0.05 were considered significant and P < 0.10 as trends after FDR correction. Fecal pH was higher (P=0.01) for SCFP-supplemented cats vs CON and exhibited a positive linear dose response (P < 0.05) at d21 and d42. Fecal score was higher (firmer; P=0.05) for SCFP-supplemented cats vs CON at d21 consistent with a linear decrease (P=0.02) in the binary comparison of fecal moisture between CON vs SCFP-supplemented cats (P=0.01) during total fecal collection. Fecal ammonia demonstrated a quadratic treatment dose response trend at d21 (P=0.09). Fecal butyrate decreased linearly with SCFP dose (P < 0.001) and was lower (P < 0.05) for SCFP-supplemented vs CON cats at d21 and d42. Total short-chain fatty acid (SCFA) decreased linearly (P=0.08) with SCFP dose and was lower (P=0.05) for SCFP-supplemented vs CON cats at d21. Species level alpha diversity decreased for CON (P=0.04) but did not change in the TRUL and TRUH groups. Shannon diversity tended to increase in TRUH (P=0.08) among a subset of 25 butyrate producers identified by the presence of butyrate pathway enzymes. Differential abundance of butyrate producers showed Acidaminococcus timonensis; CAG-83 sp900545495 and Megasphaera elsdenii decreased while Butyricicoccus pullicaecorum and Lawsonibacter 1402 linearly increased over time for TRUH cats (P < 0.05). No differences in alpha diversity or abundance were detected for any other butyrate producing taxa in TRUH nor between CON and TRUL cats. These results suggest SCFP influences several gastrointestinal outcomes in adult cats including pathways associated with SCFA production, cross-feeding, and/or absorption.