Effects of dietary cellobiose on the intestinal microbiota and excretion of nitrogen metabolites in healthy adult dogs

Large intestinal nutritional and physicochemical parameters from different dog sizes reshape canine microbiota structure and functions in vitro

Different dog sizes are associated with variations in large intestinal physiology including gut microbiota, which plays a key role in animal health. This study aims to evaluate, using the CANIM-ARCOL (Canine Mucosal Artificial Colon), the relative importance of gut microbes versus physicochemical and nutritional parameters of the canine colonic environment in shaping microbiota structure and functions. CANIM-ARCOL was set up to reproduce nutrient availability, bile acid profiles, colonic pH, and transit time from small, medium, or large dogs according to in vivo data, while bioreactors were all inoculated with a fecal sample collected from medium size dogs (n = 2). Applying different dog size parameters resulted in a positive association between size and gas or SCFA production, as well as distinct microbiota profiles as revealed by 16S Metabarcoding. Comparisons with in vivo data from canine stools and previous in vitro results obtained when CANIM-ARCOL was inoculated with fecal samples from three dog sizes revealed that environmental colonic parameters were sufficient to drive microbiota functions. However, size-related fecal microbes were necessary to accurately reproduce in vitro the colonic ecosystem of small, medium, and large dogs. For the first time, this study provides mechanistic insights on which parameters from colonic ecosystem mainly drive canine microbiota in relation to dog size. The CANIM-ARCOL can be used as a relevant in vitro platform to unravel interactions between food or pharma compounds and canine colonic microbiota, under different dog size conditions. The potential of the model will be extended soon to diseased situations (e.g. chronic enteropathies or obesity).

Prebiotic potential of pectin and cello-oligosaccharides from apple bagasse and orange peel produced by high-pressure homogenization and enzymatic hydrolysis

Apple bagasse and orange peel were subjected to high-pressure homogenization (HPH), enzymatic hydrolysis (EH) and their combination (HPHE) to study their effect on oligosaccharide production and in vitro fermentability. The application of a cellulase-pectinase mixture on the by-products generated significant quantities of cellobiose (COS-2) and pectin derived oligosaccharides (POS) which were identified as mainly methylated and acetylated oligogalacturonides with DP 2-5 (POS 2-5). When pre-treating the substrates with HPH, the release in orange peel was enhanced significantly leading to a POS content of 44.51 g/100 g peel, whereas oligosaccharide solubilization in apple bagasse was not affected. In vitro fermentation of the hydrolysates containing COS-2 and POS showed faster fermentation rates, between 6 and 10 h, and enhanced gas production, compared to those samples not subjected to enzymatic hydrolysis. Short chain fatty acid (SCFA) production was not impacted by the presence of POS and COS-2 in the induced quantities.

Canine Mucosal Artificial Colon: development of a new colonic in vitro model adapted to dog sizes

Differences in dog breed sizes are an important determinant of variations in digestive physiology, mainly related to the large intestine. In vitro gut models are increasingly used as alternatives to animal experiments for technical, cost, societal, and regulatory reasons. Up to now, only one in vitro model of the canine colon incorporates the dynamics of different canine gut regions, yet no adaptations exist to reproduce size-related digestive parameters. To address this limitation, we developed a new model of the canine colon, the CANIne Mucosal ARtificial COLon (CANIM-ARCOL), simulating main physiochemical (pH, transit time, anaerobiosis), nutritional (ileal effluent composition), and microbial (lumen and mucus-associated microbiota) parameters of this ecosystem and adapted to three dog sizes (i.e., small under 10 kg, medium 10-30 kg, and large over 30 kg). To validate the new model regarding microbiota composition and activities, in vitro fermentations were performed in bioreactors inoculated with stools from 13 dogs (4 small, 5 medium, and 4 large). After a stabilization period, microbiota profiles clearly clustered depending on dog size. Bacteroidota and Firmicutes abundances were positively correlated with dog size both in vitro and in vivo, while opposite trends were observed for Actinobacteria and Proteobacteria. As observed in vivo, microbial activity also increased with dog size in vitro, as evidenced from gas production, short-chain fatty acids, ammonia, and bile acid dehydroxylation. In line with the 3R regulation, CANIM-ARCOL could be a relevant platform to assess bilateral interactions between food and pharma compounds and gut microbiota, capturing inter-individual or breed variabilities. KEY POINTS: • CANIM-ARCOL integrates main canine physicochemical and microbial colonic parameters • Gut microbiota associated to different dog sizes is accurately maintained in vitro • The model can help to move toward personalized approach considering dog body weight.

The Impact of Fiber Source on Digestive Function, Fecal Microbiota, and Immune Response in Adult Dogs

This study evaluated the impact of different fiber sources on intestinal function, fecal microbiota, and overall health in dogs. Twelve dogs were used in a crossover design, involving three periods of 6 weeks and three diets: a low-fiber diet (CTR), a cereal-fiber and beet-pulp-supplemented diet (BRA), and a fruit-fiber-supplemented diet (FRU). Each period included a digestibility trial and fecal and blood sampling in the last week. Short-chain fatty acids (SCFAs) and microbiota taxonomy (16S rRNA Illumina-MiSeq) and functionality (Shotgun-NovaSeq 6000) were determined in the feces. General biochemistry, complete blood cells, and lymphocyte subsets were also analyzed. The fiber-supplemented diets showed lower digestibility without significant changes in the fecal consistency. The BRA diet showed higher total SCFA concentrations (p = 0.056), with increases in alpha diversity and particular beneficial genera, such as Lachnospira, Bifidobacterium, and Faecalibacterium. The BRA microbiota was also associated with an overabundance of genes related to carbohydrate and amino acid metabolism. The FRU diet had a distinct impact on the microbiota composition and functionality, leading to higher levels of CD8 lymphocytes. These findings emphasize the importance of selecting the right fiber source when formulating dog diets, as it can have a differential impact on gut microbiota and animal health.

Characterization of the Fecal Microbiome in Dogs Receiving Medical Management for Congenital Portosystemic Shunts

Background

The GI microbiome has not been characterized in dogs being medically managed for congenital portosystemic shunts (CPSS).

Objectives

To characterize the fecal microbiome in a population of dogs being medically managed for CPSS.

Animals

27 client-owned dogs.

Methods

Prospective cohort study enrollment of fecal samples was performed with follow-up data collected retrospectively. The overall fecal dysbiosis index (DI) and individual bacterial abundances were determined using real-time qPCR. Medical management, clinical findings, clinicopathologic, and outcome variables were collected, and logistic regression analyses were performed to evaluate associations between these variables and overall DI and bacterial abundances. Numerical variables were evaluated with general linear models for normality and equal variance using Shapiro-Wilk test and Levene's test, respectively.

Results

All dogs were administered a hepatic diet and lactulose, while antibiotics were used in 22 (81.5%) and acid suppressants in 7 (25.9%). Seventeen dogs (63.0%) had a DI >2. The median DI in this population was 3.02 (range 4.23–8.42), and the median DI in dogs receiving and not receiving antibiotics was 4.3 (range −4.23–8.42) and 1.52 (range −1.62–5.43), respectively. No significant association between any of the analyzed variables and the DI was identified. There was a significant association between the use of metronidazole and a larger abundance of E. coli (p = 0.024).

Conclusions and Clinical Importance

Dysbiosis appears to be common in dogs that are being medically managed for CPSS, though the clinical significance remains unclear.

Evaluation of the Effect of Different Dietary Lipid Sources on Dogs’ Faecal Microbial Population and Activities

Simple Summary

Saturated fatty acids might be a valuable source of energy to guarantee all physiological functions in companion animals. Polyunsaturated fatty acids are essential in several metabolic processes and structural body functions. In this regard, hemp oil can be used as a rich source of polyunsaturated fatty acids in animal diets. In this study, hemp seed oil and swine tallow were added to a commercial canned diet. These high-lipid-content diets (hemp diet: 55.1 g/100 kcal ME; tallow diet: 65.1 g/1000 kcal ME) were compared with one rich in starch. Following the recruitment of 12 dogs, three experimental groups were set up. At 30 days of diet administration, faeces samples were collected from each group to perform an in vitro trial and faecal bacteria count. In the first evaluation, the faecal inoculum obtained from dogs fed a diet supplemented with hemp showed higher fermentation activity and lower gas production at 24 h of incubation. The bacterial count demonstrated an increase in Lactobacillus when hemp group faeces were tested. Both in vivo and in vitro acetic acid production increased. The results obtained suggest an influence of the fatty acid profile on the microbial population.

Abstract

Lipids represent a significant energy source in dogs’ diets. Moreover, dogs need some essential fatty acids, such as linoleic and α-linolenic fatty acids, because they are not able to produce them endogenously. This study aimed to evaluate the effect of different dietary lipid sources on faecal microbial populations and activities using different evaluations. Hemp seed oil and swine tallow were tested as lipid supplements in a commercial canned diet at a ratio of 3.5% (HL1 and HL2, respectively). These diets were compared with one rich in starch (HS). Twelve dogs were recruited and equally divided into three groups. Faeces samples at 30 days were used as inoculum and incubated with three different substrates (MOS, inulin, and cellulose) using the in vitro gas production technique. The faecal cell numbers of relevant bacteria and secondary metabolites were analysed (in vivo trial). In vitro evaluation showed that the faeces of the group fed the diet with hemp supplementation had better fermentability despite lower gas production. The in vivo faecal bacterial count showed an increase in Lactobacillus spp. In the HL1 group. Moreover, a higher level of acetate was observed in both evaluations (in vitro and in vivo). These results seem to indicate a significant effect of the dietary fatty acid profile on the faecal microbial population.

Effects of the Protein Concentration and Quality in a Canned Diet on the Fecal Microbiota of Healthy Adult Cats

Feline diets can markedly differ in their protein concentration and quality, which might also affect the intestinal microbiota of cats. In the present study, 6 canned diets, differing in their protein quality (high/low, achieved by varying amounts of meat and collagen-rich ingredients) and concentration (high quality/low quality: 36.2/36.7% in dry matter (DM), 43.3/45.0% in DM and 54.9/56.1% in DM), were fed to 10 healthy adult cats for 6 weeks each. At the end of the feeding periods, fecal samples were collected to analyze the microbiota (16S rDNA sequencing) and bacterial metabolites. Increasing dietary protein concentrations increased the relative abundance of Fusobacterium and Bacteroides as well as the concentrations of ammonium and n-valerate in the feces of the cats, independently of the dietary protein quality. A lower dietary protein quality was accompanied by a higher evenness index and a higher relative abundance of Fusobacteria and Bacteroidetes in the feces when compared to the feeding of the high protein quality diets. A promotion of bacterial proteolytic activity and, in particular, increased intestinal ammonium concentrations might be undesired effects of high protein intakes in cats. Whether the long-term feeding of those diets could be critical for feline health requires further investigation.

The influence of food processing methods on serum parameters, apparent total-tract macronutrient digestibility, fecal microbiota and SCFA content in adult beagles

Food processing methods may influence the health of dogs. However, previous studies have mostly been based on a comparison of several commercial dog foods with different ingredients. In this study, eighteen adult beagles of the same age and health status (assessed by routine blood tests) were used in the experiments. This study analyzed the effects of the following different processing methods: raw, pasteurized, and high temperature sterilization (HTS) made with the same ingredients and nutrients (based on dry matter) on serum parameters, apparent total-tract macronutrient digestibility, fecal microbiota and short-chain fatty acid (SCFA) content in beagle dogs. The data showed, after a test lasting 56-days, the apparent digestibility (ATTD) of protein and fat in HTS food was 91.9%, which was significantly higher (P< 0.05) than that in dry food (89.2%, P < 0.05). The serum content of triglyceride increased in beagles fed HTS food (P < 0.05), and the number of neutrophils in beagles fed raw food and pasteurized food increased significantly (P < 0.05), and the platelet count in beagles fed raw food showed an increasing trend compared with the beagles fed HTS food. Different processing methods had an impact on the intestinal microbiota and SCFA of beagles; at least 14 genera were significantly affected by the food produced using different processing methods. In particular, the abundance of Allprevotella, Escherichia-Shigella and Turicibacter, and the total acid content were lower in beagles fed the raw diet, whereas Streptococcus, Collinsella, Bacteroides and Ruminococcus gnavus were more abundant following the HTS diet, and Lactococcus showed the highest abundance in beagles fed the pasteurized diet. This study showed that dog food produced by different processing methods affected the health of adult beagles.

Impact of the dietary inclusion of dried food residues on the apparent nutrient digestibility and the intestinal microbiota of dogs

The use of food residues for animal nutrition might imply ecological and economic advantages; however, their effects as a potential ingredient have not yet been evaluated in dogs. In the present study, four diets with 0, 5, 10 and 15% dried food residues (DFR), derived from hotel catering, were fed to 10 healthy adult dogs. At the end of each three-week feeding period, faeces and blood were collected. The apparent nutrient digestibility was calculated by the dietary inclusion of titanium dioxide as an inert marker. The results demonstrated that the apparent crude protein digestibility and ether extract digestibility decreased with increasing amounts of DFR in the diets (p < 0.05). In addition, an increase of the faecal concentrations of acetic acid, propionic acid, n-butyric acid and total short-chain fatty acids (SCFA) was observed (p < 0.05). Faecal ammonium and lactate concentrations, as well as plasma phenol and indole concentrations, were not linearly affected by the dietary inclusion of DFR. The relative abundance of Fusobacteria in the faeces of the dogs decreased, and the relative abundance of Actinobacteria and Bacteroidetes increased with increasing amounts of DFR in the diets (p < 0.05). In conclusion, the DFR seemed to be intensively fermented by the intestinal microbiota of the dogs, as indicated by the increased faecal SCFA concentrations and the shifts in the composition of the faecal microbiota. Dietary inclusion levels of up to 5% can be recommended based on our results, as the observed lower apparent crude protein and ether extract digestibility might limit the use of food residues for dogs at higher amounts.