Faecal Microbiota of Dogs Offered a Vegetarian Diet with or without the Supplementation of Feather Meal and either Cornmeal, Rye or Fermented Rye: A Preliminary Study

Nutritional and Microbiome Effects of a Partial Substitution of Poultry Meat with Hydrolyzed Feather Meal in Dog Diets

Two extruded diets isoenergetic, isonitrogenous, and isolipidic were formulated with poultry meal (control diet) as the source of animal-origin proteins (160 g/kg of feed) or with 90 g/kg of poultry meal and 70 g/kg of hydrolyzed feather meal (treated diet) and were fed to eight dogs (four adult female and four adult male English Setters). Body condition, muscle condition, and fecal consistency scores and body weight were monitored at the beginning of the trial and after 3, 7, 15, and 45 days, and no significant differences (p > 0.05) were observed between diets and between sex. Fecal samples, collected at the same time points, were analyzed for microbiota composition. No significant difference was calculated for the alpha diversity index between control diet and treated diet, nor for the diets × times of sampling interaction and for sex. Beta diversity was different (p-value 0.001) between the control and treated groups. The beta diversity between sexes was significantly different (p-value = 0.047). Linear Discriminant analysis effect size analysis revealed significant differences between dietary groups, identifying Clostridiales, Coprococcus, Bacteroides plebeius, Eubacterium biforme, Catenibacterium, and Prevotella copri as more abundant in the CTR diet, while Fusobacterium, Bacteroides, Fusobacteriaceae, Paraprevotellaceae, Enterococcus, Faecalibacterium, Enterobacteriaceae, Peptostreptococcaceae, and Clostridium spiroforme were more abundant in the treated diet. Sex differences were also significant, with 25 taxa differing between male and female dogs. Overall, the study underscores the impact of HFM and sex on gut microbiota composition in dogs, with potential implications for dietary interventions and microbiome research.

Long-term dietary intervention of the hydrolyzed feather meal on microbiota composition of adult female dogs

This research delves into the impact of substitution of 7% of poultry meal (PM) with hydrolyzed feather meal (HFM) on the animal performance and fecal microbiota of dogs. The study was conducted on six adult female English setter dogs, split into control (CTR), and treated (TRT) dietary treatment groups, with similarity for age, initial body weight, and body condition score. During 45-days, body weight, body condition score, muscle condition score, fecal consistency score and microbiota were monitored at the beginning of the trial and after 3, 7, 15 and 45 days. No significant differences (P > 0.05) were observed for these parameters over the whole period of the trial, neither in relation to diet, nor to time, nor to the interaction diet x time. Significant differences were observed for alpha between diets and the TRT group displayed higher evenness compared to the CTR group. Beta diversity analysis revealed distinctions in microbiota composition between the CTR and TRT groups, with the former demonstrating higher biodiversity. Discriminant analysis highlighted 9 significant taxa and 6 of them were significantly different at the Kruskal Wallis test between diets. The results showed an increase in relative abundance (RA) for the CTR group of Streptococcus, Colinsella stercoris, Ruminococcus gnavus, and Bacteroides coprophilus. Conversely, higher RA was observed in the TRT group for Peptostreptococcaceae and Bacteroides uniformis. These findings indicated that the inclusion of hydrolyzed feather meal in the diet of dogs is well accepted and do not have adverse effects in the parameters analyzed.

Comparison of the fecal microbiota of adult healthy dogs fed a plant-based (vegan) or an animal-based diet

Purpose

Pet guardians are increasingly seeking vegan dog foods. However, research on the impact of these diets on gastrointestinal (GI) physiology and health is limited. In humans, vegan diets modify the GI microbiota, increasing beneficial digestive microorganisms. This study aimed to examine the canine fecal microbiota in response to a vegan diet compared to an animal-based diet.

Methods

Sixty-one client-owned healthy adult dogs completed a randomized, double-blinded longitudinal study. Dogs were randomly assigned into two groups that were fed either a commercial extruded animal-based diet (MEAT, n = 30) or an experimental extruded vegan diet (PLANT, n = 31) for 12 weeks. Fecal collections occurred at the start of the experimental period and after 3 months of exclusively feeding either diet. Bacterial DNA was extracted from the feces, and the V4 region of the 16S rRNA gene was amplified using PCR and sequenced on Illumina MiSeq. Beta-diversity was measured using Jaccard and Bray-Curtis distances, and the PERMANOVA was used to assess for differences in fecal microbiota within and between groups. Alpha-diversity indices for richness, evenness, and diversity, as well as relative abundance, were calculated and compared between groups.

Results

Beta-diversity differences occurred between diet groups at exit time-point with differences on Bray-Curtis distances at the family and genus levels (p = 0.007 and p = 0.001, respectively), and for the Jaccard distance at the family and genus level (p = 0.006 and p = 0.011, respectively). Significant differences in alpha-diversity occurred when comparing the PLANT to the MEAT group at the exit time-point with the PLANT group having a lower evenness (p = 0.012), but no significant differences in richness (p = 0.188), or diversity (p = 0.06). At exit-timepoint, compared to the MEAT group, the relative abundance of Fusobacterium, Bacteroides, and Campylobacter was lower in the PLANT group. The relative abundance of Fusobacterium decreased over time in the PLANT group, while no change was observed in the MEAT group.

Conclusion

These results indicate that vegan diets may change the canine gut microbiota. Future studies are warranted to confirm our results and determine long-term effects of vegan diets on the canine gut microbiome.

Efficacy of vitamin D2 in maintaining serum total vitamin D concentrations and bone mineralisation in adult dogs fed a plant-based (vegan) diet in a 3-month randomised trial

Dogs are considered omnivores based on their evolution consuming diets including animal tissue. Few feeding trials evaluating the nutritional suitability of exclusively plant-based (vegan) diets in dogs have been published, and the efficacy of vitamin D2 in maintaining canine serum vitamin D levels has not been clearly determined. A blinded dietary trial included sixty-one healthy desexed adult dogs: thirty-one fed an experimental extruded vegan diet (PLANT) and thirty fed a commercial extruded meat-based diet (MEAT) for 3 months. Dogs were screened via veterinary examination and routine laboratory analyses prior to enrolment, at baseline and exit timepoints. Body composition was measured by dual-energy X-ray absorptiometry and blood was collected for vitamin D profiling. All dogs maintained health parameters, body weight and composition throughout the study. Dogs maintained on PLANT demonstrated a significant reduction in platelet count, creatinine, blood urea nitrogen and cholesterol, though values remained within normal reference ranges. Dogs fed PLANT also demonstrated a shift from vitamin D3 to vitamin D2 metabolites, though total vitamin D analogue levels were unchanged, with the exception of 24,25-dihydroxyvitamin D. Bone mineral content and density did not differ from baseline values. Health status was maintained in dogs fed PLANT and vitamin D2 appeared efficacious in maintaining serum total vitamin D concentrations and bone mineralisation. Findings support the hypothesis that PLANT was comparable to MEAT for maintenance of healthy adult dogs for at least 3 months and identified areas where further research is warranted to elucidate the potential risks and benefits of plant-based (vegan) diets.

Fecal microbiota of the synanthropic golden jackal (Canis aureus)

The golden jackal (Canis aureus), is a medium canid carnivore widespread throughout the Mediterranean region and expanding into Europe. This species thrives near human settlements and is implicated in zoonoses such as rabies. This study explores for the first time, the golden jackal fecal microbiota. We analyzed 111 fecal samples of wild golden jackals using 16S rRNA amplicon sequencing the connection of the microbiome to animal characteristics, burden of pathogens and geographic and climate characteristics. We further compared the fecal microbiota of the golden jackal to the black-backed jackal and domestic dog. We found that the golden jackal fecal microbiota is dominated by the phyla Bacteroidota, Fusobacteriota and Firmicutes. The golden jackal fecal microbiota was associated with different variables, including geographic region, age-class, exposure to rabies oral vaccine, fecal parasites and toxoplasmosis. A remarkable variation in the relative abundance of different taxa was also found associated with different variables, such as age-class. Linear discriminant analysis effect size (LEfSe) analysis found abundance of specific taxons in each region, Megasphaera genus in group 1, Megamonas genus in group 2 and Bacteroides coprocola species in group 3. We also found a different composition between the fecal microbiota of the golden jackal, blacked-backed jackal and the domestic dog. Furthermore, LEfSe analysis found abundance of Fusobacterium and Bacteroides genera in the golden jackal, Clostridia class in blacked-backed jackal and Megamonas genus in domestic dog. The golden jackal fecal microbiota is influenced by multiple factors including host traits and pathogen burden. The characterization of the microbiota of this thriving species may aid in mapping its spread and proximity to human settlements. Moreover, understanding the jackal microbiota could inform the study of potential animal and human health risks and inform control measures.

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

Dietary fiber in dog food is reported to promote healthy gut microbiota, but few studies have investigated the effects of whole-grain cereals, which contain a variety of fiber types and other bioactive compounds. The aim of the present study was to compare the effects of diets containing whole-grain rye (RYE), oats (OAT) and wheat (WHE) on fecal microbiota and short-chain fatty acid production. Eighteen dogs were fed three experimental diets, each for four weeks, in a cross-over design. Fecal samples were collected at the end of each diet period. Analysis of 16S rRNA gene amplicons showed that family Lachnospiraceae and genus Bacteroides were the gut microbial groups most affected by diet, with lowest relative abundance following consumption of RYE and a trend for a corresponding increase in genus Prevotella_9. Fecal acetate and propionate concentrations were higher after consumption of RYE compared with OAT. In conclusion, rye had the strongest effect on gut microbiota and short-chain fatty acids, although the implications for dog gut health are not yet elucidated.

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

BACKGROUND

Rye intake has been associated with beneficial effects on health in human interventions, possibly due to 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 and with 2-2.5 months between diet periods. The diets were similar 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

Faecal microbiota composition, 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.

Nutrient Digestibility of a Vegetarian Diet with or without the Supplementation of Feather Meal and Either Corn Meal, Fermented Rye or Rye and Its Effect on Fecal Quality in Dogs

Cereals with low environmental input like rye and animal by-products which cannot be used for human food like feather meal are receiving growing interest as sustainable feed sources. Thus, eight Beagle dogs were included in a 4 × 4 Latin Square design and received a vegetarian basic diet or the same diets supplemented with hydrolyzed feather meal (2.7%) and either 20.1% of corn meal, 60.4% of fermented rye or 20.1% of rye as is basis (moisture content of the diets about 42%). Compared to other groups the dry matter (DM) content of feces from dogs fed the basic diet was higher (30.0%, p < 0.05), while dogs fed the basic diet + rye had the lowest DM-content (26.5%, p < 0.05). However, the fecal scores were considered to be within an acceptable range (well-formed and firm). Starch digestibility was lower (p < 0.05) for dogs fed the basic diet + corn meal. The dogs showed a high and identical acceptance (scoring of food intake) of the experimental diets. As a comparable quality of feces and a high nutrient digestibility were observed when rye was used in the experimental diets-it can be considered an alternative carbohydrate source in dog foods.