Effects of rye inclusion in dog food on fecal microbiota and short-chain fatty acids

Abstract

BackgroundRye intake has been associated with beneficial effects on health in human interventions, possibly due to soluble dietary fiber in rye. In dogs, few studies have explored the effects on health of dietary fiber in general, and rye fiber in particular. The aim of this study was to investigate how inclusion of rye, compared with wheat, influenced fecal microbiota composition, short chain fatty acids (SCFA) and apparent total tract digestibility (ATTD) in dogs. Six male Beagle dogs (mean age 4.6 years, SEM 0.95 years; mean body weight 14.6 kg, SEM 0.32 kg) were fed three experimental diets, each for 21 days, including an adaptation period of six days. The diets were as similar as possible regarding energy and protein, but had different carbohydrate sources (refined wheat (W), whole grain rye (R), or an equal mixture of both (RW)) comprising 50% of total weight on a dry matter (DM) basis. The diets were baked and titanium dioxide was added for ATTD determination. Fecal samples were collected before and in the end of each experimental period. Fecal microbiota was analyzed by sequencing 16S rRNA gene amplicons and fecal SCFA by high-performance liquid chromatography. Crude protein, crude fat, neutral detergent fiber, and gross energy (GE) in food and feces were analyzed and ATTD of each was determined. Univariate and multivariate statistical methods were applied in data evaluation.Results:Microbiota composition, in feces, differed depending on diet (P=0.002), with samples collected after consumption of the R diet differing from baseline. This was primarily because of a shift in proportion of Prevotella, which increased significantly after consumption of the R diet (P<0.001). No significant differences were found for SCFA, but there was a tendency (P<0.06) for higher molar proportions of acetic acid following consumption of the R diet. The ATTD of crude protein, crude fat, neutral detergent fiber, and GE was lower after consumption of the R diet compared with the other diets (P<0.05).Conclusions:Consumption of the R diet, but not RW or W diets, was associated with specific shifts in microbial community composition and function, but also with lower ATTD.

Effects of whole-grain cereals on fecal microbiota and short-chain fatty acids in dogs - A comparison of rye, oats and wheat

“…Statistical signi cance was likely not reached due to large inter-individual variation, and larger sample size would perhaps con rm a signi cant difference between diets. In agreement with ndings in the present study, our previous study showed signi cantly higher Prevotella abundance following the diet with highest inclusion of rye than following the wheat diet 21 . However, in that study whole-grain rye was compared to re ned wheat and the dietary inclusion level of rye was higher (50% of DM).…”

“…Catenibacterium is a common bacterial member of the gut microbiota in dogs, yet often of relatively low abundance 45,51,52 . In the present study it was one of the most abundant genera, with highest abundance in samples collected after diet R. In contrast, in our previous study this taxon decreased in abundance from a baseline level on adding rye to the diet 21 . The reason for the discrepancy is unknown.…”

“…On investigating the effects on individual microbial genera and OTUs, we observed that genus Bacteroides and several OTUs belonging to that genus were least abundant in samples collected from dogs after diet R and highest after diet W. In a previous study by our research group, a decrease in Bacteroides after a diet with 50% rye inclusion, compared with samples collected before the diet period, was a factor of major importance for the difference in general microbial composition 21 . Decreased abundance of Bacteroides has been reported in studies on humans and pigs investigating the effects of rye kernel bread compared with re ned wheat 22 and an arabinoxylan-supplemented diet compared with a control diet 46 .…”

“…The diets were nutritionally complete and balanced according to FEDIAF guidelines 28 . The level of grain inclusion was set at 25%, as fed, based on previous results 21 . The diets were also composed to be similar in terms of protein and metabolizable energy content (Table 2).…”

“…We have previously compared the effects of whole-grain rye and re ned wheat on the fecal microbiota in dogs 21 . In that study, we observed an increase in genus Prevotella relative to baseline values when rye was included as 50% of dry matter in the diet.…”