In vitro fermentation characteristics of novel fibers, coconut endosperm fiber and chicory pulp, using canine fecal inoculum

Green banana flour as a novel functional ingredient in retorted feline diets

Green banana flour (GBF) is a novel ingredient that is high in resistant starch and could be a dietary fiber source in companion animal nutrition. In addition, with its light brown color and pectin content, GBF could potentially serve as a natural color additive and thickening agent in pet food manufacturing. The purpose of this research is to evaluate different sources of GBF, the effect of GBF on texture and color in canned foods, and its effect on apparent total tract digestibility (ATTD), fecal characteristics, and fecal fermentative end-products in healthy adult cats. Prior to the feline study, different sources of GBF were analyzed for chemical composition, manufacturing properties, true metabolizable energy, and fermentability. For the feline feeding trial, all treatment diets were formulated to meet or exceed the Association of American Feed Control Officials (Association of American Feed Control Officials (AAFCO) 2020. Official Publication. Champaign, IL.) guidelines for adult cat maintenance. There were five dietary treatments: rice control (4% rice flour), potato control (4% dehydrated potato flakes), 1% GBF (1% GBF and 3% rice flour), 2% GBF (2% GBF and 2% rice flour), and 4% GBF. All treatment diets were analyzed for texture and color. The animal study was conducted using a completely randomized design with 39 adult domestic cats. There was a 7-d diet adaptation period followed by a baseline fresh fecal collection to determine fecal score, pH, short-chain fatty acid, branched-chain fatty acid, phenol, indole, ammonia, and microbiota. The treatment period lasted for 21 d and a total fecal collection was performed during the last 4 d of this period to determine the ATTD. A fresh fecal sample was also collected during the total fecal collection to evaluate fecal score, pH, metabolites, and microbiota. The MIXED model procedures of SAS version 9.4 were used for statistical analysis. Treatment diets containing GBF had a lower hardness from the texture profile analysis (P < 0.05). For color analysis, the 4% GBF diet was darker in color compared with the rice diet (P < 0.05). There was no difference in food intake, fecal output, or ATTD of macronutrients among the treatment groups (P > 0.05). There was no interaction of treatment and time or main effects shown in fecal score, pH, metabolites, or microbiota diversity (P > 0.05). In conclusion, adding GBF to canned diets may affect the texture and color of the product, but GBF was comparable to traditional carbohydrate sources, rice, and potato, from a nutritional aspect.

High-protein dried distillers grains in dog diets: diet digestibility and palatability, intestinal fermentation products, and fecal microbiota

This study aimed to evaluate the effects of high-protein dried distillers grains (HPDDG) on palatability and metabolizable energy (ME) of the diet, apparent total tract digestibility (ATTD) of nutrients and energy, intestinal fermentation products, and fecal microbiota in dogs. Four diets containing 0, 70, 140, and 210 g/kg of HPDDG were manufactured. To evaluate the ME and the ATTD of macronutrients of HPDDG itself, an additional test diet was manufactured containing 70% of the control diet formula (0 g/kg) and 300 g/kg of HPDDG. Fifteen adult Beagle dogs were distributed in a randomized block design, with two periods of 15 d each (n = 6). The HPDDG digestibility was obtained using the Matterson substitution method. For the palatability test, 16 adult dogs were used, comparing the diets: 0 vs. 70 g/kg of HPDDG and 0 vs. 210 g/kg of HPDDG. The ATTD of HPDDG were: dry matter = 85.5%, crude protein = 91.2%, and acid-hydrolyzed ether extract = 84.6% and the ME content was 5,041.8 kcal/kg. The ATTD of macronutrients and ME of the diets and the fecal dry matter, score, pH, and ammonia of the dogs did not differ among treatments (P > 0.05). There was a linear increase in the fecal concentrations of valeric acid with the inclusion of HPDDG in the diet (P < 0.05). Streptococcus and Megamonas genera reduced linearly (P < 0.05), and Blautia, Lachnospira, Clostridiales, and Prevotella genera showed a quadratic response to the inclusion of HPDDG in the diet (P < 0.05). Alpha-diversity results showed an increase (P < 0.05) in the number of operational taxonomic units and Shannon index and a trend (P = 0.065) for a linear increase in the Chao-1 index with the dietary inclusion of HPDDG. Dogs preferred the 210 g/kg diet over the 0 g/kg HPDDG diet (P < 0.05). These results demonstrate that the HPDDG evaluated does not affect the utilization of nutrients in the diet, but it may modulate the fecal microbiome of dogs. In addition, HPDDG may contribute to diet palatability for dogs.

Digestibility of a Lignocellulose Supplemented Diet and Fecal Quality in Beagle Dogs

Lignocellulose (LC) might be used as a substitute fiber source for dogs as a strategy to decrease energy density and enhance gastrointestinal functionality. The objective of the present study was to compare the effects of including different levels of LC on apparent nutrient digestibility and fecal parameters (dry matter (DM), fecal score, and daily fecal output), as well as fecal fatty acid concentrations. Four diets were tested: control diet (no supplementation of LC; LC0), and three control diets diluted with increasing levels of LC: 1, 2, and 4% (LC1, LC2, and LC4). Six Beagle dogs (BW 17.1 kg ± 1.22) participated in a crossover experimental design. Before each experimental period, five days were used as a wash-out period. The fecal consistency was scored based on a 5-point scale (1 = very hard; 2 = solid, well-formed “optimum”; 3 = soft, still formed; 4 = pasty, slushy; and 5 = watery diarrhea). The results demonstrated that the organic matter apparent digestibility (p = 0.01) and nitrogen-free extract (NFE) (p < 0.01) was significantly lower for dogs fed LC4 compared to those fed LC0. Dogs fed LC2 and LC4 had a lower fecal consistency score (2.39 and 2.18, respectively; p < 0.05). The fecal DM was significantly the highest (p < 0.01), and the daily fecal output on fresh matter was lower (p < 0.05) when dogs were fed the LC4 diet compared with the LC0 diet. Including LC at 1% in the diet resulted in significantly higher fecal acidic pH levels. However, no differences among treatments were noted regarding fecal fatty acid concentrations.

In Vitro Assessment of Hydrolysed Collagen Fermentation Using Domestic Cat (Felis catus) Faecal Inocula

The gastrointestinal microbiome has a range of roles in the host, including the production of beneficial fermentation end products such as butyrate, which are typically associated with fermentation of plant fibres. However, domestic cats are obligate carnivores and do not require carbohydrates. It has been hypothesised that in the wild, collagenous parts of prey—the so-called animal-derived fermentable substrates (ADFS) such as tendons and cartilage—may be fermented by the cat’s gastrointestinal microbiome. However, little research has been conducted on ADFS in the domestic cat. Faecal inoculum was obtained from domestic cats either consuming a high carbohydrate (protein:fat:carbohydrate ratio of 35:20:28 (% dry matter basis)) or high protein (protein:fat:carbohydrate ratio of 75:19:1 (% dry matter basis)) diet. ADFS (hydrolysed collagen, cat hair, and cartilage) were used in a series of static in vitro digestions and fermentations. Concentrations of organic acids and ammonia were measured after 24 h of fermentation, and the culture community of microbes was characterised. The type of inoculum used affected the fermentation profile produced by the ADFS. Butyrate concentrations were highest when hydrolysed collagen was fermented with high protein inoculum (p < 0.05). In contrast, butyrate was not detectable when hydrolysed collagen was fermented in high carbohydrate inoculum (p < 0.05). The microbiome of the domestic cat may be able to ferment ADFS to provide beneficial concentrations of butyrate.

In vitro digestion and microbial fermentation of dried food residues, a potential “new” component for pet food, and different non-digestible carbohydrate sources

Food residues are often fed to dogs in private households and might also be a potential “new” ingredient for pet food in the future. As food residues might contain not only digestible, but also fermentable substrates, an effect on the intestinal microbiota can be assumed. In the present study, two batches of dried food residues (DFR) collected from hotels in Crete were microbially fermented in an in vitro batch culture system with canine fecal inoculum: non-sterile DFR including meat (DFRm), sterile DFR including meat (DFRms) and sterile DFR without meat (DFRwms). Different non-digestible carbohydrate sources (beet pulp, wheat bran, inulin, carrot pomace, brewer´s spent grains, cellulose and lignocellulose) were included for comparison. Inulin, cellulose and lignocellulose were only used as raw materials, while the other test substrates were incubated as raw and enzymatically pre-digested substrates. After incubation for 24 hours, the raw food residues markedly increased the concentrations of bacterial metabolites in the fermenters, although smaller effects were observed for the DFRwms. When the enzymatically pre-digested food residues were incubated, the effects were more pronounced for the DFRms and DFRwms. In general, when compared with the other test substrates, the food residues were microbially fermented to a comparable or partly higher extent. Interestingly, high n-butyrate concentrations were measured in the inocula, both after incubation of the raw and pre-digested food residues. In conclusion, the food residues contained enzymatically digestible and microbially fermentable substrates. If considered as a potential future ingredient for pet food, a standardization of the collection and processing of food residues might be necessary in order to reduce compositional variability and varying effects on the intestinal microbiota.

Nutrient digestibility and fecal characteristics, microbiota, and metabolites in dogs fed human-grade foods

Human-grade (HG) pet foods are commercially available, but they have not been well studied. Our objective was to determine the apparent total tract digestibility (ATTD) of HG pet foods and evaluate their effects on fecal characteristics, microbiota, and metabolites, serum metabolites, and hematology of dogs. Twelve dogs (mean age = 5.5 ± 1.0; BW = 11.6 ± 1.6 kg) were used in a replicated 4 × 4 Latin square design (n = 12/treatment). The diets included 1) Chicken and Brown Rice Recipe (extruded; Blue Buffalo); 2) Roasted Meals Tender Chicken Recipe (fresh; Freshpet); 3) Beef and Russet Potato Recipe (HG beef; JustFoodForDogs); and 4) Chicken and White Rice Recipe (HG chicken; JustFoodForDogs). Each period consisted of 28 d, with a 6-d diet transition phase, 16 d of consuming 100% of the diet, a 5-d phase for fecal collection, and 1 d for blood collection. All data were analyzed using the Mixed Models procedure of SAS 9.4. Dogs fed the extruded diet required a higher (P < 0.05) daily food intake (dry matter basis, DMB) to maintain BW. The ATTD of dry matter (DM), organic matter (OM), energy, and acid-hydrolyzed fat (AHF) were greater (P < 0.05) in dogs fed the HG diets than those fed the fresh diet, and greater (P < 0.05) in dogs fed the fresh diet than those fed the extruded diet. Crude protein ATTD was lower (P < 0.05) for dogs fed the extruded diet than those fed all other diets. Dogs fed the extruded diet had greater (P < 0.05) fecal output (as-is; DMB) than dogs fed fresh (1.5-1.7 times greater) or HG foods (2.0-2.9 times greater). There were no differences in fecal pH, scores, and metabolites, but microbiota were affected by diet. Dogs fed HG beef had higher (P < 0.05) relative abundance of Bacteroidetes and lower (P < 0.05) relative abundance of Firmicutes than dogs fed the fresh or HG chicken diets. The Actinobacteria, Fusobacteria, Proteobacteria, and Spirochaetes phyla were unchanged (P > 0.05), but diet modified the relative abundance of nearly 20 bacterial genera. Similar to previous reports, these data demonstrate that the fecal microbiota of dogs fed HG or fresh diets is markedly different than those consuming extruded diets, likely due to ingredient, nutrient, and processing differences. Serum metabolites and hematology were not greatly affected by diet. In conclusion, the HG pet foods tested resulted in significantly reduced fecal output, were highly digestible, maintained fecal characteristics, serum chemistry, and hematology, and modified the fecal microbiota of dogs.

Effect of a novel animal milk oligosaccharide biosimilar on the gut microbial communities and metabolites of in vitro incubations using feline and canine fecal inocula

Milk oligosaccharides (MO) confer multiple potential physiological benefits, such as the selective growth promotion of beneficial microbiota, inhibition of enteric pathogen growth and adhesion to enterocytes, maturation of the gut mucosal barrier, and modulation of the gastrointestinal immune system. This study was conducted to determine the fermentation potential of GNU100, an animal MO biosimilar, in an in vitro system using healthy canine and feline fecal inocula. Single feline and single canine fecal samples were used to inoculate a batch fermentation system. Tubes containing a blank control (BNC), GNU100 at 0.5% (5 g/L; GNU1), or GNU100 at 1.0% (10 g/L; GNU2) were incubated for 48 h. Gas pressure, pH, lactate, short-chain fatty acids (SCFA; acetate, propionate, and butyrate), and branched-chain fatty acids (BCFA; isobutyrate, isovalerate, and valerate) were measured after 6, 24, and 48 h. Ammonium and microbiota (total bacteria by flow cytometry and Pet-16Seq; Lactobacillus and Bifidobacterium by quantitative polymerase chain reaction ) were measured after 24 and 48 h. Data were analyzed using the Mixed Models procedure of SAS. Substrates were considered to be a fixed effect and replicates considered to be a random effect. Tukey's multiple comparison analysis was used to compare least squares means, with differences considered significant with P < 0.05. In feline and canine incubations, SCFA increases were greater (P < 0.0001) in GNU100 compared with BNC, with acetate making up the largest SCFA proportion (P < 0.0001). GNU100 cultures led to greater increases (P < 0.0001) in lactate and ammonium than BNC in the feline incubations. GNU100 cultures led to greater increases (P < 0.0001) in ammonium than BNC in canine incubations and greater increases (P < 0.0001) in BCFA than BNC in feline incubations. Pet-16Seq microbial profiles from the feline and canine fecal incubations exhibited a modulation after GNU100 fermentation, with a reduction of the genera Escherichia/Shigella and Salmonella. In feline incubations, Bifidobacterium populations had greater increases (P < 0.0001) in GNU100 than BNC. In feline incubations, Lactobacillus populations had greater increases (P = 0.01) in GNU100 than BNC, with GNU1 leading to greater increases (P = 0.02) in Lactobacillus than BNC tubes in canine incubations. Overall, this study demonstrated that GNU100 was fermented in an in vitro fermentation system inoculated with canine and feline microbiota, resulting in the growth of beneficial bacteria and the production of SCFA, BCFA, and ammonium.

Organic matter disappearance and production of short- and branched-chain fatty acids from selected fiber sources used in pet foods by a canine in vitro fermentation model1

Dietary fibers can influence a dog’s overall health, but high concentrations of soluble dietary fibers can cause soft stools. An in vitro model could be useful to predict the rate fibers are fermented once they reach the colon. Pet food companies are constantly searching for new ingredients to differentiate their products from competitors. Miscanthus grass (MG), pea fiber (PF), and sorghum bran (SB) are novel fiber sources that could be alternatives to standards like cellulose (CE) and beet pulp (BP). The objectives of the study were to determine the effects of fiber source on organic matter disappearance (OMD), estimated organic matter disappearance (EOMD), and fermentation end-product concentrations using an in vitro fermentation procedure and dog fecal inoculum. Total dietary fiber (TDF) residues from MG, CE, BP, PF, and SB were fermented in vitro with buffered dog feces. Fecal samples were collected and maintained in anaerobic conditions until the dilution and inoculation. Test tubes containing the fibrous substrates were incubated for 4, 8, and 12 h at 39 °C. Short-chain fatty acids (SCFA), branched-chain fatty acids (BCFA), OMD, and EOMD were determined for each fiber source and time point. Beet pulp had the highest OMD, EOMD, and SCFA production of all tested fiber sources (38.6% OMD, 26.2% EOMD, 2.72 mmol SCFA/g of substrate). Sorghum bran led to greater concentrations of BCFA (59.86 µmol/g of substrate) and intermediate OMD and EOMD compared to the other tested fibers. Cellulose and MG were poorly fermented with the lowest OMD, EOMD, SCFA, and BCFA compared to other fibers. In conclusion, MG could be used as an insoluble minimally fermentable replacement fiber for CE in dog foods.