289 In vitro fermentation characteristics of Emulgold acacia fiber using canine fecal inoculum

Abstract Emulgold (EG) is a highly concentrated source of soluble dietary fiber extracted from the natural resin of the acacia tree. Acacia fiber is known for its prebiotic effects in humans but has not been well studied in dogs. This study was conducted to assess how EG and other fibers commonly used in pet foods (cellulose, inulin, and pectin) affected fermentability and canine microbiota populations using an in vitro fermentation system. Fresh fecal samples were collected from healthy adult dogs (n = 3) and pooled to serve as inoculum. Fermentation media aliquots were collected at 0, 6, 12, and 18 h for measurement of pH, gas production, short-chain fatty acid (SCFA) concentrations, and microbiota populations. Blank-corrected data were analyzed using the PROC MIXED of SAS, with fiber and time as main effects. Sequence data were analyzed using QIIME2. Significance was declared at P ≤ 0.05. In this study, distinct fermentation patterns were observed among the different fiber substrates over time. Fermentation media pH (P ≤ 0.01) decreased, while gas (P ≤ 0.01) and SCFA (P = 0.01) production increased over time. EG, inulin, and pectin tubes had a greater (P ≤ 0.01) decrease in media pH than cellulose tubes. Pectin and inulin tubes had a greater (P < 0.01) increase in gas production than those containing EG and cellulose. A greater (P < 0.01) increase in SCFA concentrations was observed in EG, inulin, and pectin tubes than cellulose tubes. Alpha diversity analysis showed that bacterial richness (observed features; P = 0.03) and diversity (Shannon diversity; P = 0.02) were highest after 18 hours of fermentation. Also, EG tubes had a greater (P ≤ 0.01) number of observed features and Shannon Index than other fibers. β-diversity analysis based on weighted and unweighted UniFrac distances demonstrated differences due to time and fiber. Bacterial communities at 0 h differed (P < 0.01) from those at 6, 12 or 18 h. In addition, β-diversity was different (P < 0.01) among fiber sources. Specifically, unweighted UniFrac distances showed separate clustering of bacterial communities within tubes containing EG, cellulose, and pectin, indicating distinct bacterial community structure among these substrates. The bacterial community associated with inulin exhibited similarities to those observed in tubes containing EG and pectin. Weighted UniFrac distances showed that the bacterial community of EG and cellulose tubes had clusters separate from those containing pectin and inulin. Differences in the relative abundances of approximately 40 bacterial genera were affected by time and fiber type. Specifically, tubes containing EG had a greater increase in Bacteroides while cellulose tubes had a greater increase in Lactobacillus than other fibers. Inulin tubes had a greater increase in Bifidobacterium and Dubosiella than other fibers. Overall, this study showed that Emulgold results in increased bacterial richness and diversity with significantly less gas production when compared with pectin and inulin.