The aim was to evaluate the effects of yeast probiotic on diet digestibility, fermentative metabolites, and fecal microbiota of dogs submitted to dietary change. Sixteen dogs were divided into two groups of eight dogs each: control, without, and with probiotic, receiving 0.12 g/dog/day of live Saccharomyces cerevisiae yeast. The dogs were fed a lower protein and fiber diet for 21 days and then changed to a higher protein and fiber diet until day 49. Yeast supplementation did not statistically influence diet digestibility. The probiotic group had a lower fecal concentration of total biogenic amines (days 21 and 49), ammonia (day 23), and aromatic compounds and a higher fecal concentration of butyrate (p < 0.05). The probiotic group showed a lower dysbiosis index, a higher abundance (p < 0.05) of Bifidobacterium (days 35 and 49) and Turicibacter, and a lower abundance of Lactobacillus and E. coli (p < 0.05). Beta diversity demonstrated a clear differentiation in the gut microbiota between the control and probiotic groups on day 49. The control group showed upregulation in genes related to virulence factors, antibiotic resistance, and osmotic stress. The results indicated that the live yeast evaluated can have beneficial effects on intestinal functionality of dogs.

Background: Direct-fed microbials (DFM), such as Bacillus subtilis and Bacillus licheniformis, may improve gut functionality of the host by favouring non-pathogenic bacteria and reducing the formation of putrefactive compounds. The aim of this study was to assess the nutrient digestibility, faecal characteristics and intestinal-fermentation products in dogs fed diets with Bacillus subtilis and Bacillus licheniformis. Sixteen dogs were randomly divided into two groups. Every eight dogs were fed with the control diet or the diet with the addition of 62.5 g of DFM (B. subtilis and B. licheniformis)/ton. Diets were provided throughout a 20-day adaptation period, followed by 5 days of total faecal collection. Nutrient digestibility and the metabolisable energy of the diets, plus the dogs’ faecal characteristics and intestinal fermentation products were assessed. Results: There were no differences in nutrient digestibility (P > 0.05). However, DFM supplementation improved faecal score and resulted in less fetid faeces (P < 0.001). DFM inclusion reduced (P < 0.05) the biogenic amines concentration: putrescine, spermidine and cadaverine, besides the concentration of phenols and quinoline. Conclusions: The use of B. subtillis and B. licheniformis as DFM reduce the concentration of nitrogen fermentation products in faeces and faecal odour, but the digestibility of nutrients is not altered in dogs.

Feed additives, such as prebiotics and essential oils, are used in pet foods and can affect digestibility, palatability, and intestinal functionality of dogs. The combined effects of yeast cell wall and oregano essential oil on apparent total tract digestibility (ATTD) and palatability of diet, intestinal fermentation products, and fecal microbiota in dogs were analyzed. Eighteen adult dogs were fed for 20 days with three dry extruded diets for adult dogs: control (without the additive), a diet containing 1.5 kg/ton of yeast cell wall and oregano essential oil (1.5YCO), and a diet containing 3.0 kg/ton of yeast cell wall and oregano essential oil (3.0YCO). The inclusion of both levels of YCO reduced the intake ratio. The addition of 3.0YCO reduced the ATTD of dry matter, compared to the control group (p < 0.05). There were greater putrescine and cadaverine concentrations and lower histamine and ammonia (p < 0.05) in the feces of dogs fed 3.0YCO. In addition, fecal odor of dogs fed YCO was less fetid than the control group (p < 0.05). There was greater fecal bacterial diversity in dogs fed with both dietary concentrations of YCO evaluated (p < 0.05). Dogs fed 1.5YCO and 3.0YCO showed higher relative abundance of Blautia and Faecalibacterium and lower abundance of Streptococcus (p < 0.05) in the feces, in comparison to the control group. Given the modulation of microorganisms considered beneficial and the lower fecal concentrations of histamine, phenols, and ammonia, the YCO blend resulted in indicators of improvement of intestinal functionality in dogs.

This study aimed to evaluate the effects of yeast extract on the apparent total tract digestibility (ATTD) of nutrients, metabolisable energy (ME), and palatability of diet, and on intestinal fermentative products in dogs. In addition, we also evaluated the ATTD and ME of yeast extract in dogs. Four diets containing 0, 40, 80, and 120 g/kg of yeast extract were evaluated. Diet digestibility, faecal characteristics, and intestinal fermentative products were evaluated in 12 adult Beagle dogs distributed in a randomised block design, with two periods of 10 days each. Yeast extract digestibility was obtained by regression analysis. Sixteen adult dogs were used for the palatability test to compare the diets: 0 vs. 40 g/kg yeast extract. The yeast extract presented ATTD of dry matter = 77.3%, crude protein (CP) = 55.7%, acid-hydrolysed ether extract (AHEE) = 73.8%, and ME = 4947.3 kcal/kg. There was a linear reduction in ATTD of CP and AHEE in the diets with yeast extract inclusion (p <.05). There was a linear increase in faecal concentration of total short-chain fatty acids (SCFA) and a linear reduction in faecal pH with the dietary inclusion of yeast extract (p <.05). Dogs preferred the 40 g/kg over the 0 g/kg yeast extract diet (p <.001). The dietary inclusion of up to 120 g/kg yeast extract led to lower ATTD of CP and AHEE, and higher faecal concentration of SCFA. Furthermore, a diet with yeast extract was more palatable to dogs.

This research aimed to evaluate the apparent total tract digestibility (ATTD) of nutrients, metabolisable energy (ME) and palatability of the diet, as well as products of intestinal fermentation and faecal microbiota of dogs fed with dried apple. For this purpose, three experiments were performed. In Experiment I, digestibility and ME of four diets containing 0%, 3%, 6% and 9% dried apple were evaluated, in addition to the faecal characteristics of the dogs. The diets were offered to eight adult dogs, distributed in double Latin square (4 × 4), totalling eight repetitions per treatment. In Experiment II, products of intestinal fermentation and faecal microbiota from 16 adult dogs fed diets containing 0% and 9% dried apple for 30 d (n = 8) were evaluated. Finally, Experiment III compared the dietary preference of 0 vs. 9% dried apple using 15 adult dogs. The inclusion of dried apple in the diet (p < 0.05) showed a linear reduction in the ATTD of dry matter (DM), crude protein (CP), and acid hydrolysed ether extract (EEA), and a linear increase in the ATTD of total dietary fibre (TDF). Consumption of 9% of dried apple increased faecal butyrate and reduced propionate and ammonia (p < 0.05). With this diet, there was also an increase (p < 0.05) in the faecal concentration of Faecalibacterium, Erysipelatoclostridium, Blautia, and Bacteroides. No differences were found in the palatability of the diets. The inclusion of up to 9% of dried apple in the diet reduces the digestibility of nutrients and does not influence the dogs’ food preference; however, it improves some indicators of dogs’ intestinal functionality.