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.

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.

Prediction Equations for In Vitro Ileal Disappearance of Dry Matter and Crude Protein Based on Chemical Composition in Dog Diets

The aims of this study were to determine in vitro ileal disappearance (IVID) of dry matter (DM) and crude protein (CP) in commercial dog diets and to develop equations for predicting the IVID of DM and CP in dog diets based on chemical composition. Eighteen commercial dog diets were analyzed for IVID of DM and CP using a two-step in vitro procedure for dogs. The diet samples in flasks with digestive enzymes were incubated for 2 h and 4 h to simulate digestion in the stomach and the small intestine, respectively. The contents of CP, ether extract, neutral detergent fiber (NDF), and ash in the diets ranged from 14.4 to 42.5%, 3.5 to 23.5%, 6.4 to 34.6%, and 4.9 to 10.0%, respectively, on an as-is basis. The NDF contents were negatively correlated with the IVID of DM and CP (r = -0.73 and r = -0.62, respectively; p < 0.05). The most suitable prediction equations for the IVID of DM and CP in the dog diets were: IVID of DM (%) = 81.33 + 0.46 × CP - 0.77 × NDF, R² = 0.78; IVID of CP (%) = 81.25 + 0.33 × CP - 0.49 × NDF, R² = 0.64, where all nutrients were in % on an as-is basis. In conclusion, dry matter and protein utilization of dog diets based on in vitro digestibility assays can be estimated fairly well using protein and fiber concentrations as independent variables.

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.

Fine cassava fibre utilization as a dietary fibre source for dogs: Effects on kibble characteristics, diet digestibility and palatability, faecal metabolites and microbiota

The objective was to evaluate through three experiments the effects of a fine cassava fibre (CA: 106 µm) on kibble characteristics, coefficients of total tract apparent digestibility (CTTAD) of macronutrients, diet palatability and faecal metabolites and microbiota of dogs. Dietary treatments consisted of a control diet (CO), without an added fibre source and with 4.3% total dietary fibre (TDF), and a diet with 9.6% CA (106 µm), with 8.4% TDF. Experiment I evaluated the physical characteristics of the kibbles. The palatability test was evaluated in experiment II, which compared the diets CO versus CA. In experiment III, 12 adult dogs were randomly assigned to one of the two dietary treatments for 15 days, totalling six replicates/treatment, to assess the CTTAD of macronutrients; faecal characteristics, faecal metabolites and microbiota. The expansion index, kibble size and friability of diets with CA were higher than the CO (p < 0.05). Additionally, the CA diet presented higher palatability than the CO (p < 0.05) but did not affect CTTAD except for those of fibre (p > 0.05). Moreover, a greater faecal concentration of acetate, butyrate and total short-chain fatty acids (SCFA) and a lower faecal concentration of phenol, indole and isobutyrate were observed in dogs fed the CA diet (p < 0.05). Dogs fed with the CA diet presented a greater bacterial diversity and richness and a greater abundance of genera considered to be beneficial for gut health, such as Blautia, Faecalibacterium and Fusobacterium when compared to the CO group (p < 0.05). The inclusion of 9.6% of a fine CA improves the expansion of kibbles and diet palatability without affecting most of the CTTAD of nutrients. Besides, it improves the production of some SCFA and modulates the faecal microbiota of dogs.

Effect of Yeast Saccharomyces cerevisiae as a Probiotic on Diet Digestibility, Fermentative Metabolites, and Composition and Functional Potential of the Fecal Microbiota of Dogs Submitted to an Abrupt Dietary Change

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.

Alterations in Healthy Adult Canine Faecal Microbiome and Selected Metabolites as a Result of Feeding a Commercial Complete Synbiotic Diet with Enterococcus faecium NCIMB 10415

In dogs, the use of probiotics for preventive or therapeutic purposes has become increasingly common, however the evidence for beneficial effects are often limited. The aim of this study was to investigate the effects of feeding a diet containing Enterococcus faecium NCIMB 10415 on faecal quality, faecal short-chain fatty acid concentrations, serum concentrations of cholesterol, triglycerides, cobalamin and folate as well as faecal microbiome in adult dogs. Eleven healthy client owned dogs were enrolled in a randomized, double-blinded crossover study. All dogs were fed the same balanced diet with or without incorporation of Enterococcus faecium NCIMB 10415 for 16 days each. Blood and faecal samples were collected at baseline and during the feeding trial and owners recorded daily faecal scores. An Enterococcus spp. ASV, likely representing E. faecium NCIMB 10415 was detected in the faecal microbiome of some dogs 18-19 days after withdrawal of oral supplementation. Inclusion of E. faecium decreased circulating cholesterol (p = 0.008) compared to baseline. There were no differences in cholesterol concentrations between diets. Owners reported 0.6 ± 0.3) days less of loose stools compared to the control diet. Comparing to baseline, both diets significantly increased faecal concentration of acetate and butyrate, decreased serum cobalamin and increased faecal microbial diversity. Decreased serum cobalamin, and increased faecal acetate correlated with decreases in the Fusobacterium, Streptococcus, Blautia, and Peptoclostridium. Except for effects on circulating cholesterol and faecal score, effects were observed regardless of the addition of E. faecium. It is therefore likely that these effects can be contributed to dietary prebiotic effects on the faecal microbiome.

The Mechanism of Important Components in Canine Fecal Microbiota Transplantation

Fecal microbiota transplantation (FMT) is a potential treatment for many intestinal diseases. In dogs, FMT has been shown to have positive regulation effects in treating Clostridioides difficile infection (CDI), inflammatory bowel disease (IBD), canine parvovirus (CPV) enteritis, acute diarrhea (AD), and acute hemorrhagic diarrhea syndrome (AHDS). FMT involves transplanting the functional components of a donor's feces into the gastrointestinal tract of the recipient. The effective components of FMT not only include commensal bacteria, but also include viruses, fungi, bacterial metabolites, and immunoglobulin A (IgA) from the donor feces. By affecting microbiota and regulating host immunity, these components can help the recipient to restore their microbial community, improve their intestinal barrier, and induce anti-inflammation in their intestines, thereby affecting the development of diseases. In addition to the above components, mucin proteins and intestinal epithelial cells (IECs) may be functional ingredients in FMT as well. In addition to the abovementioned indications, FMT is also thought to be useful in treating some other diseases in dogs. Consequently, when preparing FMT fecal material, it is important to preserve the functional components involved. Meanwhile, appropriate fecal material delivery methods should be chosen according to the mechanisms these components act by in FMT.

Effects of a Specific Pre- and Probiotic Combination and Parent Stock Vaccination on Performance and Bacterial Communities in Broilers Challenged with a Multidrug-Resistant Escherichia coli

Antibiotic resistance poses a risk for human and animal health, leading to a growing demand for effective alternatives. Combining nutritional tools and parent stock vaccination could be an approach to achieve sufficient protection against bacterial infections in poultry. In an Escherichia coli O1/O18 challenge trial, we investigated the protective effects of feeding diets containing Enterococcus faecium DSM 7134 and fructooligosaccharides (FOS) combined with specific parent stock vaccination in 225 ROSS 308 broilers. Data on performance parameters, intestinal microbial composition and metabolites, and antibiotic resistance genes (sul1-3, dhfr1a, SHV-12) were obtained. E. faecium and FOS combined with parent stock vaccination led to the highest body weights, which were significantly higher than those of controls throughout the experiment and decreased the relative abundance of Proteobacteria in the crop digesta compared to that in the positive control. However, cumulative feed conversation remained unaffected by the strategies. Birds receiving the pre-/probiotic combination showed lower cecal pH levels and higher crop L-lactate concentrations than the controls, whereas copy numbers of dhfr1a (trimethoprim resistance) and SHV-12 (extended-spectrum beta-lactamase) genes were only decreased in broilers from vaccinated hens compared to those in the challenged control. In conclusion, prophylactic administration of E. faecium and FOS in combination with parent stock vaccination can have complementary effects by improving broiler weight gain and stimulating intestinal bacterial metabolism, which may be beneficial for maintaining gut health in terms of Escherichia coli infection.

Effects of Oral Glutamine Supplementation, Birthweight and Age on Colonic Morphology and Microbiome Development in Male Suckling Piglets

Mortality, impaired development and metabolic dysfunctions of suckling low-birthweight piglets may be influenced by modulating the intestinal microbiome through glutamine supplementation. Therefore, this study examined whether glutamine supplementation may affect the colonic development and microbiome composition of male low- and normal-birthweight piglets at 5 and 12 days of age. Suckling piglets were supplemented orally with glutamine or alanine. Colonic digesta samples were obtained for 16S rDNA sequencing, determination of bacterial metabolites and histomorphological tissue analyses. Glutamine-supplemented piglets had lower concentrations of cadaverine and spermidine in the colonic digesta (p < 0.05) and a higher number of CD3+ colonic intraepithelial lymphocytes compared to alanine-supplemented piglets (p < 0.05). Low-birthweight piglets were characterised by a lower relative abundance of Firmicutes, the genera Negativibacillus and Faecalibacterium and a higher abundance of Alistipes (p < 0.05). Concentrations of cadaverine and total biogenic amines (p < 0.05) and CD3+ intraepithelial lymphocytes (p < 0.05) were lower in low- compared with normal-birthweight piglets. In comparison to the factor age, glutamine supplementation and birthweight were associated with minor changes in microbial and histological characteristics of the colon, indicating that ontogenetic factors play a more important role in intestinal development.

Dietary Ground Flaxseed Increases Serum Alpha-Linolenic Acid Concentrations in Adult Cats

We evaluated effects of dietary ground flaxseed on fecal and serum alpha-linolenic acid (ALA) concentrations, nutrient digestibility, and stool quality in female and male adult cats (n = 20 (8 males, 12 females); 3.95 ± 1.49 years of age (mean ± SD); 3.88 ± 0.82 kg BW). We hypothesized that adding ground flaxseed would increase serum ALA compared with feeding no flax, without changing nutrient digestibility. Cats were fed as-is 2.6% added-flaxseed (flax, n = 10) or no-flax (control, n = 10) diets (2.66 vs. 0.78% ALA of total fatty acids; crude protein 35%, fat 20%, fiber 3% as-fed) twice daily to maintain body weight for 28 days. Fecal collections were conducted on days 23−27 for total-tract nutrient digestibility, stool quality (scale 1−5; 1 = watery diarrhea, 5 = hard, dry, crumbly) and long-chain fatty acid (LCFA) analyses. Blood was collected on days 0, 14, and 28 for serum LCFA and chemistry analysis. Digestibility and fecal data were analyzed by ANOVA (SAS v9.4, Cary, NC, USA) and a repeated measures ANOVA for serum ALA. Flax-fed cats, compared with control-fed, had greater (p < 0.05) serum ALA after 14 days (4.00 vs. 0.71 µg/mL) and 28 days (7.83 and 3.67 µg/mL). No differences were observed in stool quality, and dry matter, protein, fat, and ALA digestibility. However, metabolizable energy was greater in the flax vs. control diet (4.18 vs. 3.91 kcal/g; p < 0.05). Overall, these data demonstrate that ground flaxseed added to cat diets increases serum ALA within 14 days, with no detriments to nutrient digestibility. We conclude that flaxseed can be used as a bioavailable source of ALA in cat diets.

The effect of age and processing on the in vitro fermentation of fibrous feedstuffs by labrador retriever dogs

Dietary fibre substances in dog foods are composed of cell wall polysaccharides, non-cellulose polysaccharides, and structural non-polysaccharides. The purpose of this study was to determine the effects of dog age and heat-steam pressure (extruding process) on the in vitro fermentation of fibrous feedstuffs (sugar beet pulp, tomato pomace, wheat bran, corn bran, and rice bran) to be included in dog foods. The fibrous feedstuffs were incubated with a fermentation medium mixture and faeces inoculum, which were collected from two 6 month old (puppy), two 2 year old (adult), and two 8 year old (geriatric) dogs. The in vitro cumulative gas production (at 6, 12, 18, 24, 36, and 48 h), true-organic matter disappearance (T-OMd) (at 6, 12, 24, and 48 h), and molarities of short chain fatty acids (SCFA) (acetic, propionic, and butyric acids; AA, PA, and BA) in fermentation fluid (at 24 h) of fibrous feedstuffs were determined. The extruding process increased the in vitro cumulative gas production of rice bran (at 12, 18, 24, and 48 h) and wheat bran (at 6, 12, 24, and 36 h) (P < 0.05). In addition, in vitro cumulative gas production values of tomato pomace (at 12, 18, 24, 36, and 48 h) were reduced by the extruding process (P < 0.05). The extruding process increased the in vitro T-OMd values of sugar beet pulp (at 6, 12, and 24 h), wheat and rice bran (at 6 and 12 h), and the molarities of AA, BA, and total SCFA of the in vitro fermentation fluid of sugar beet pulp and wheat bran (P < 0.05). The in vitro cumulative gas production values of tomato pomace from faecal inoculums of the puppy and adult dogs were higher than that of the geriatric dog (P < 0.05). The in vitro T-OMd of sugar beet pulp (at 48 h) and extruded corn bran (at 6 h) with faecal inoculums of adult dog was higher than those of inoculum from puppy faeces (P < 0.05). The molarity of AA of tomato pomace with adult dog's faecal inoculum was higher than those from puppy and geriatric dog (P < 0.05). The molarities of AA, BA, and total SCFA with corn bran from faeces inoculums of the puppy and adult dog was higher than that of the geriatric dog (P < 0.05). The molarities of AA and total SCFA of the in vitro fermentation fluid of extruded rice bran with faecal inoculums from the geriatric dogs was higher than those with faecal inoculums from the puppy and adult dogs (P < 0.05). As a result, the extruding process positively affected the in vitro fermentation values of sugar beet pulp, wheat bran, and rice bran. Furthermore, the organic acid molarities of the in vitro fermentation fluid of extruded rice bran from the geriatric dog was higher than those from the puppy and adult dogs. Sugar beet pulp, tomato pomace, wheat bran, and corn bran can be used as a source of fibre in food for puppy, adult, and geriatric large 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.

Performance, health, bacterial metabolites and intestinal histomorphology in does and growing rabbits fed diets with increasing lignocellulose-to-cellulose proportions

Adequate levels of dietary fibre can reduce the risk of intestinal health disorders in rabbits after weaning. Therefore, it was the aim of the study to investigate the impact of different lignocellulose and cellulose addition to rabbits' diets on performance and intestinal traits in lactating does and weaned rabbits. A total of 60 rabbit does (4.41 ± 0.45 kg body weight) were fed isonitrogenous diets with lignocellulose and cellulose inclusion rates [%] of 0/8, 2/6, 4/4, 6/2 and 8/0, resulting in dietary lignin-to-cellulose ratios of 0.26, 0.30, 0.32, 0.34 and 0.40, respectively. The diets were fed from 4 d ante partum (a.p.) until day 28 post partum (p.p. weaning). After weaning, 40 young rabbits from each feeding group were fed the same diets for 12 d, when 10 rabbits per group were sacrificed. Body weight gain (BWG), feed intake and feed conversion ratio were obtained. Gastrointestinal content and gut tissue were obtained from the growing rabbits and pH, short-chain fatty acids (SCFA) concentration and gut morphology were investigated. Digestive disorders were scored, and the sanitary risk index was calculated. Does fed the highest lignocellulose addition increased their feed intake [g · kg BW^-1 · d^-1] in the first two weeks p.p. (p < 0.001) and increased BWG (p < 0.001) but without impact on their offsprings' performance. Weaned rabbits fed the highest lignocellulose inclusion showed a reduced feed intake and increased sanitary risk index. Additionally, a higher number of rabbits showed intestinal disorders for a short time (1-2 d, p < 0.001). In the colon content, a higher pH and a lower dry matter content were observed in this group. Caecal contents of 40-d old rabbits showed lower total SCFA, acetate and propionate and higher i-valerate and L-lactate concentrations after feeding diets with high lignocellulose contents. The diet did not influence the acetate-to-propionate ratio. No histomorphological changes were observed in the jejunum, while crypt depth and width were reduced in the caecum of weaned rabbits fed diets with lignocellulose addition. It can be concluded that different proportions of lignocellulose to cellulose addition to rabbits' diets have an impact on health and performance with differences between does and weaned rabbits. While a high lignocellulose inclusion proved beneficial for does, for weaned rabbits, a lower addition should be preferred.

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.

Effect of orange fibre on nutrient digestibility and fermentation products in faeces of cats fed kibble diets

The aim of the present study was to compare orange fibre, beet pulp and inulin as fibre sources for cats. A control diet (CON) was formulated without inclusion of a fibre source. Further experimental diets were also based on diet CON but were supplemented with 1% orange fibre (diet 1%OF); 3% orange fibre (diet 3%OF); 3% beet pulp (diet 3%BP) or 1% inulin (diet 1%IN). Forty cats were used in a randomised block design (4 blocks of 10 cats, 2 animals per food in each block, totalling 8 animals per treatment). Each block lasted 20 d, with 10 d of adaptation, 10 d of faecal collection for digestibility as well as evaluation of pH-value and fermentation products. The digestibility of dry matter, organic matter, crude protein, ether extract, starch and gross energy did not vary between diets. In diet 1%OF, dietary fibre revealed a greater digestibility than in diet CON (p < 0.05). Faecal production was higher in cats fed diets 3%OF and 3%BP than in those fed diet 1%IN (p < 0.05). Faecal concentrations of acetate and total short-chain fatty acids were higher for cats fed diet 3%BP than for those fed diets 1%IN and CON (p < 0.05), while diets 1%OF and 3%OF showed intermediate results. Faecal propionate concentration was higher for cats fed diet 3%BP, intermediate for diets 1%OF, 3%OF and 1%IN and lower for animals fed diet CON (p < 0.05). Compared with diets CON and 1%IN, the faecal concentration of tyramine was higher for cats fed diet 3%OF (p < 0.05). Orange fibre was fermentable; up to 3% inclusion it did not interfere with the digestibility of nutrients, faecal score and faecal moisture content, and promoted the formation of short-chain fatty acids and tyramine by the intestinal microbiota, with possible effects on intestinal function.

Feeding Fiber-Bound Polyphenol Ingredients at Different Levels Modulates Colonic Postbiotics to Improve Gut Health in Dogs

Simple Summary

Microbes present in the large intestine of humans and companion animals produce bioactive metabolites from host-ingested food. These bioactive metabolites can influence host health. A prior study in dogs that were healthy or had chronic enteritis/gastroenteritis showed that stool quality improved when they ate food containing a fiber bundle made from fibers of pecan shells, flax seed, cranberry, citrus, and beet. In addition, eating food containing the fiber bundle resulted in the gut bacteria shifting from digesting mainly protein to digesting mainly carbohydrates. The present study tested the impact of the fiber bundle at a lower range of concentrations in dogs. Fecal levels of several bioactive metabolites with beneficial antioxidant or anti-inflammatory properties increased after dogs consumed food with the fiber bundle, though no changes in the bacteria or their functional pathways were observed. Stool quality remained in the acceptable range. These results suggest that the gut bacteria were able to digest the fiber bundle to produce beneficial bioactive metabolites to improve host health.

Abstract

This study assessed changes in canine fecal metabolites and microbiota with the consumption of foods with increasing concentrations of a fiber bundle including pecan shells, flax seed, and powders of cranberry, citrus, and beet that was previously shown (at 14% w/w) to improve stool quality, shift fecal bacterial metabolism from proteolysis to saccharolysis, increase abundance of saccharolytic bacteria, and decrease abundance of proteolytic bacteria. In this study, 48 healthy adult dogs were split evenly to consume different inclusion levels (0%, 1%, 2%, and 4%) of the fiber bundle for a 31-day period following a 28-day pre-feed period. Increases from baseline in the fecal short-chain fatty acids butyric acid, valeric acid, and hexanoic acid were observed only in the dogs that consumed the food with the 4% fiber bundle. With addition of any level of the fiber bundle, increases were seen in the polyphenols hesperidin, hesperetin, ponciretin, secoisolariciresinol diglucoside, secoisolariciresinol, and enterodiol. However, fecal microbiota and their metabolism, and stool scores were largely unaffected by the fiber bundle. Overall, addition of the fiber bundle appeared to increase bioactive metabolites of increased antioxidant and anti-inflammatory potency for beneficial to health and, at levels ≥4%, shifted gut bacterial metabolism toward saccharolysis.

Dietary supplementation with fiber, "biotics," and spray-dried plasma affects apparent total tract macronutrient digestibility and the fecal characteristics, fecal microbiota, and immune function of adult dogs

A variety of functional ingredients, including fibers, prebiotics, probiotics, and postbiotics may be added to pet foods to support gastrointestinal and immune health. While many of these ingredients have been tested individually, commercial foods often include blends that also require testing. This study was conducted to evaluate the effects of diets containing blends of fibers, "biotics," and/or spray-dried plasma on apparent total tract digestibility (ATTD), stool quality, fecal microbiota and metabolites, and immune health outcomes of adult dogs. A total of 12 healthy adult intact English pointer dogs (6 M, 6 F; age = 6.4 ± 2.0 yr; BW = 25.8 ± 2.6 kg) were used in a replicated 3 × 3 Latin square design to test diets formulated to: 1) contain a low concentration of fermentative substances (control diet, CT); 2) be enriched with a fiber-prebiotic-probiotic blend (FPPB); and 3) be enriched with a fiber-prebiotic-probiotic blend + immune-modulating ingredients (iFFPB). In each 28-d period, 22 d of diet adaptation was followed by a 5-d fecal collection phase and 1 d for blood sample collection. All data were analyzed using SAS 9.4, with significance being P < 0.05 and trends being P < 0.10. FPPB and iFPPB diets led to shifts in numerous outcome measures. Dry matter (DM), organic matter, fat, fiber, and energy ATTD were lower (P < 0.01), fecal scores were lower (P < 0.01; firmer stools), and fecal DM% was higher (P < 0.0001) in dogs fed FPPB or iFPPB than those fed CT. Serum triglycerides and cholesterol were lower (P < 0.01) in dogs fed FPPB or iFPPB than those fed CT. Fecal protein catabolites (isobutyrate, isovalerate, indole, and ammonia) and butyrate were lower (P < 0.05), while fecal immunoglobulin A (IgA) was higher (P < 0.01) in dogs fed FPPB and iFPPB than those fed CT. Fecal microbiota populations were affected by diet, with alpha-diversity being lower (P < 0.05) in dogs fed iFPPB and the relative abundance of 20 bacterial genera being altered in dogs fed FPPB or iFPPB compared with CT. The circulating helper T cell:cytotoxic T cell ratio was higher (P < 0.05) in dogs fed iFPPB than those fed CT. Circulating B cells were lower (P < 0.05) in dogs fed FPPB than those fed iFPPB, and lower (P < 0.05) in dogs fed iFPPB than those fed CT. Our results demonstrate that feeding a fiber-prebiotic-probiotic blend may provide many benefits to canine health, including improved stool quality, beneficial shifts to fecal microbiota and metabolite profiles, reduced blood lipids, and increased fecal IgA.

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.

Effects of Dietary Cereal and Protein Source on Fiber Digestibility, Composition, and Metabolic Activity of the Intestinal Microbiota in Weaner Piglets

Simple Summary

Rye and rapeseed meal can be alternative feed components for weaner piglets instead of wheat and soybean meal. Both components can help to meet current challenges in pig nutrition, such as increasingly dry weather conditions and the high amount of imported soybean. Since they contain more and differently composed fiber, effects on digestive physiology and intestinal microbiota might help to maintain gut health and prevent post-weaning diarrhea. This study shows that despite a similar composition of the large intestinal microbiota, the higher amount and solubility of complex carbohydrates from rye lead to a higher fermentative activity compared to wheat, which is considered a beneficial effect. The high amount of insoluble dietary fiber in rapeseed-based diets lowered bacterial metabolic activity and caused a shift toward insoluble fiber degrading bacteria.

Abstract

This study aimed to investigate the effect of fiber-rich rye and rapeseed meal (RSM) compared to wheat and soybean meal (SBM) on fiber digestibility and the composition and metabolic activity of intestinal microbiota. At weaning, 88 piglets were allocated to four feeding groups: wheat/SBM, wheat/RSM, rye/SBM, and rye/RSM. Dietary inclusion level was 48% for rye and wheat, 25% for SBM, and 30% for RSM. Piglets were euthanized after 33 days for collection of digesta and feces. Samples were analyzed for dry matter and non-starch-polysaccharide (NSP) digestibility, bacterial metabolites, and relative abundance of microbiota. Rye-based diets had higher concentrations of soluble NSP than wheat-based diets. RSM-diets were higher in insoluble NSP compared to SBM. Rye-fed piglets showed a higher colonic and fecal digestibility of NSP (p < 0.001, p = 0.001, respectively). RSM-fed piglets showed a lower colonic and fecal digestibility of NSP than SBM-fed piglets (p < 0.001). Rye increased jejunal and colonic concentration of short-chain fatty acids (SCFA) compared to wheat (p < 0.001, p = 0.016, respectively). RSM-fed pigs showed a lower jejunal concentration of SCFA (p = 0.001) than SBM-fed pigs. Relative abundance of Firmicutes was higher (p = 0.039) and of Proteobacteria lower (p = 0.002) in rye-fed pigs compared to wheat. RSM reduced Firmicutes and increased Actinobacteria (jejunum, colon, feces: p < 0.050), jejunal Proteobacteria (p = 0.019) and colonic Bacteroidetes (p = 0.014). Despite a similar composition of the colonic microbiota, the higher amount and solubility of NSP from rye resulted in an increased fermentative activity compared to wheat. The high amount of insoluble dietary fiber in RSM-based diets reduced bacterial metabolic activity and caused a shift toward insoluble fiber degrading bacteria. Further research should focus on host–microbiota interaction to improve feeding concepts with a targeted use of dietary fiber.

Altered fecal microbiota, IgA, and fermentative end-products in adult dogs fed prebiotics and a nonviable Lactobacillus acidophilus

A study investigating the use of a nonviable Lactobacillus acidophilus (NVL: Culbac; TransAgra, Storm Lake, IA) and a mixed prebiotic (MP) blend (beet pulp, fructooligosaccharide (FOS), mannanoligosaccharide (MOS), inulin, and kelp) was done to evaluate changes in fecal microbiota, fermentative end products, and gut immune health in healthy female and male adult Beagle dogs (n = 24; 5.74 ± 2.18 yr; 9.30 ± 1.32 kg). The study protocol was first approved by the facility's Institutional Animal Care and Use Committee (Summit Ridge Farms; Susquehanna, PA) and followed throughout. Each of four test diets (control, NVL, MP, and MP + NVL [formulated to crude protein 25%, crude fat 14%, crude fiber 10% as-fed]) was fed once daily to maintain body weight for 21 d in a randomized-crossover design (four treatment periods and four washout periods). Fecal samples were collected on days 0 and 21 only for immunoglobulin A (IgA) and microbiota evaluation (16S rRNA V4 region and qPCR for Escherichia coli and Bifidobacterium), and fecal fermentative end-products and fecal pH were assessed only on day 21. Over the test periods, apparent total tract nutrient digestibility and stool quality were assessed. Data were analyzed by ANOVA (SAS v9.4, Cary, NC) or Kruskal-Wallis for between-diet effects, and paired t-test or Wilcoxon for time effects. Statistical significance was set at P ≤ 0.05. Apparent total tract nutrient digestibility revealed feeding MP-containing diets resulted in lower (P < 0.05) crude protein and fat digestibility vs. control and NVL diets. When dogs were fed MP, they had lower (P < 0.05) fecal pH compared with control and NVL diets, whereas fecal pH was lower in (P < 0.05) MP + NVL- vs. NVL-fed dogs. Fecal E. coli was (P < 0.05) lower at day 21 vs. day 0 when dogs were fed MP. Fecal Fusobacterium spp. was lower (P < 0.05) in both MP diets vs. control. Fecal Lactobacillus spp. increased (P < 0.05) from baseline with MP. Both diets with MP elicited greater (P < 0.05) fecal acetate and propionate concentration vs. control diet. At day 21, fecal IgA was greater (P < 0.05) in MP and MP + NVL compared with NVL diet. Only when dogs were fed MP did they have increased (P < 0.05) fecal IgA from day 21 vs. day 0. The MP + NVL diet decreased (P < 0.05) fecal isovalerate, isobutyrate, phenol, and indole vs. control. Overall, the MP elicited the most changes on microbiota, fermentative end-products, and IgA. Further investigation into NVL's gut health benefits is warranted.

Effect of dietary inclusion of dried apple pomace on faecal butyrate concentration and modulation of gut microbiota in 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.

Orange fibre effects on nutrient digestibility, fermentation products in faeces and digesta mean retention time in dogs

Fermentable fibres are used in commercial dog food to promote intestinal health by providing substrates for better metabolic activity of the gut microbiota. Brazil is the world's largest producer of oranges, from which it is possible to obtain fibre with a relevant soluble fraction. The present study compared the effects of two inclusions of orange fibre (1% and 3%, on as fed basis) with a negative control (without addition of fibre source) and two positive controls, beet pulp (3%) and purified inulin (1%), totalling five extruded diets for dogs. The experiment followed a randomised block design with 4 blocks of 10 dogs, 2 dogs per food in each block, totalling 8 dogs per diet. The apparent total tract nutrient digestibility was determined by total faecal collection. Faecal pH and fermentation product content were also measured. The digesta mean retention time (DMRT) was evaluated using plastic markers. The inclusion of a 3% fibre source in diets with 3% orange fibre and beet pulp reduced DM, OM, and energy digestibility (p < 0.05). Diets with 3% orange fibre, beet pulp and 1% inulin presented lower crude protein digestibility than the control (p < 0.05). Dietary fibre digestibility was higher for orange fibre-supplemented diets than inulin (p < 0.05). Beet pulp and 3% orange fibre inclusions resulted in increased moisture content in the faeces of dogs (p < 0.05) but did not alter DMRT. Total short-chain fatty acids were higher than the control in the faeces of dogs fed both orange fibre levels and the beet pulp-supplemented diet (p < 0.05), and the inulin diet-fed dogs presented intermediate values. Butyrate was higher in the faeces of dogs fed the diets supplemented with 1% and 3% orange fibre (p < 0.05), and similar values to the control were observed for beet pulp- and inulin-fed animals. Thus, it was concluded that orange fibre presented higher apparent total tract dietary fibre digestibility than beet pulp and had a fermentation profile in the colon that promoted the generation of butyrate, an effect not observed for inulin and beet pulp.

Lignocellulose as an insoluble fiber source in poultry nutrition: a review

Extensive research in recent years into the use of various fiber sources in poultry nutrition has led to the perception that dietary fiber is more than a simple diet diluent. Several studies showed that the feeding of insoluble fiber sources such as oat hulls, sunflower hulls or wood shavings may affect digestive physiology and function improving chickens health and growth performance. In this context, the effect of lignocellulose as an insoluble dietary fiber source is increasingly being investigated. Lignocellulose is a component of plant cell walls and consists mainly of the insoluble carbohydrate polymers cellulose and hemicelluloses as well as the phenolic polymer lignin. Lignocellulose is chemically and physicochemically different from other insoluble fiber sources and thus possibly has different effects on poultry compared to traditional fiber sources. Several studies investigated the effect of dietary lignocellulose on growth performance, nutrient digestibility, gastrointestinal tract development and intestinal microbiota in broilers and laying hens. Studies differed in terms of feed formulation and lignocellulose inclusion level as well as products of different suppliers were used. The results obtained are inconsistent; beneficial, indifferent or detrimental effects of feeding lignocellulose were observed, so that a final assessment of lignocellulose as a “novel” insoluble fiber source is difficult. This review article summarizes the results of studies in connection with the feeding of lignocellulose to poultry, compares them with those that have used other insoluble fiber sources and illuminates the possible mechanisms of action.

Effects of diet on body weight, body composition, metabolic status, and physical activity levels of adult female dogs after spay surgery

Neutering is a risk factor for pet obesity, which reduces the quality and length of life. Dietary interventions may serve as preventive and therapeutic options for pet obesity. The objective of this study was to evaluate the effects of specially formulated diets on body weight (BW), body composition, and blood hormones and metabolites of adult female dogs after spay surgery. All procedures were approved by the University of Illinois Institutional Animal Care and Use Committee prior to experimentation. Twenty-eight healthy adult intact female Beagles (3.02 ± 0.7 yr; 10.28 ± 0.8 kg; body condition score [BCS]: 4.98 ± 0.57) were used in a longitudinal study. Twenty-four dogs were spayed and randomly allotted to one of three experimental diets: 1) moderate-protein, moderate-fiber diet (control; COSP), 2) high-protein, high-fiber diet (HP-HF), or 3) high-protein, high-fiber diet plus omega-3 and medium-chain fatty acids (HP-HF-O). Four dogs were sham-operated and fed the control diet (COSH). Food intake, BW, BCS, blood hormones and metabolites, body composition (via dual-energy X-ray absorptiometry scans), and voluntary physical activity (via Actical devices) were measured over time. After spay, dogs were fed to maintain BW for 12 wk (restricted phase), then allowed to overeat for 12 wk (ad libitum phase). Change from baseline data was analyzed for treatment, time, and treatment × time effects as well as treatment, feeding regimen, and treatment × feeding regimen effects. During the first 12 wk, HP-HF and HP-HF-O had lower (P < 0.01) blood cholesterol than COSH and COSP. During the second 12 wk, HP-HF and HP-HF-O ate more (P < 0.01) food (g/d) than COSH. BCS change for COSP was greater (P < 0.01) than COSH from week 21 to 24, but HP-HF and HP-HF-O were not different. When comparing data by feeding regimen, HP-HF and HP-HF-O had a greater reduction in serum cholesterol (P < 0.001) than COSH and COSP. During the second 12 wk, all spayed dogs consumed more (P < 0.01) food than COSH. However, COSH, HP-HF, and HP-HF-O had a lower (P < 0.001) increase in BCS than COSP. HP-HF-O and COSH had similar serum leptin during weeks 12 to 24. COSP had higher (P ≤ 0.01) serum C-reactive protein than HP-HF-O. Overall, body fat increase in COSP was greater (P < 0.05) than for COSH at week 24, while HP-HF and HP-HF-O were intermediate. Our results indicate that an HP-HF diet can limit weight gain and body fat increase and attenuate serum cholesterol, triglycerides, and leptin concentrations in dogs after spay surgery.

Effect of feeding different levels of lignocellulose on performance, nutrient digestibility, excreta dry matter, and intestinal microbiota in slow growing broilers

Lignocellulose is a constituent of plant cell walls and might be used as a fiber source in poultry nutrition. The current study investigated the impact of increasing dietary levels of lignocellulose on performance, nutrient digestibility, excreta DM, intestinal microbiota, and bacterial metabolites in slow growing broilers. At an age of 10 wk, 60 male broilers of an intercross line (New Hampshire × White Leghorn) were allocated to cages and fed isoenergetic and isonitrogenous diets containing 0.8% (LC1), 5% (LC2), or 10% (LC3) lignocellulose. After 23 D of feeding, broilers were killed and digesta samples of ileum and excreta analyzed for nutrient digestibility and DM. Cecal contents were analyzed for microbial composition and metabolites. Broiler performance was not affected by feeding dietary lignocellulose. LC3 fed broilers showed reduced ileal digestibility of protein compared to chickens fed LC1 (P = 0.003). Moreover, increasing levels of dietary lignocellulose reduced apparent digestibility of organic matter and gross energy (P < 0.001). Feeding of lignocellulose had no impact on the excreta DM of broilers. Increasing levels of dietary lignocellulose lowered cecal counts of Escherichia/Hafnia/Shigella (P = 0.029) and reduced the total concentration of short-chain fatty acids (P < 0.001), lactate (P < 0.05), and ammonia (P = 0.009). The molar ratio of cecal acetic acid was higher in LC3 fed broilers (P < 0.001), while the proportions of cecal propionic acid and n-butyric acid were higher in LC1 and LC2 fed chickens (P < 0.001). Correlation analyses indicated that dietary lignocellulose was negatively related to the total concentration of cecal bacterial metabolites (P < 0.001). In conclusion, the feeding of lignocellulose did not affect growth performance, but impaired nutrient digestibility of slow growing broilers. While minor changes in cecal microbial composition were detected, cecal bacterial metabolite concentrations were significantly reduced with increasing levels of dietary lignocellulose. These findings suggest that lignocellulose is not extensively degraded by bacteria residing in the large intestine of broilers.

A commercial grain-free diet does not decrease plasma amino acids and taurine status but increases bile acid excretion when fed to Labrador Retrievers

Grain-free diets tend to have greater inclusions of pulses in contrast to grain-based diets. In 2018, the Food and Drug Administration (FDA) released a statement that grain-free diets may be related to the development of canine dilated cardiomyopathy (DCM). However, all dog foods met regulatory minimums for nutrient inclusion recommended by the Association of American Feed Controls Official. In some FDA case reports, but not all, dogs diagnosed with DCM also had low concentrations of plasma or whole blood taurine; thus, we hypothesized that feeding these diets will result in reduced taurine status from baseline measures. The objective of this study was to determine the effects of feeding a grain-free diet to large-breed dogs on taurine status and overall health. Eight Labrador Retrievers (four males and four females; Four Rivers Kennel, MO) were individually housed and fed a commercial complete and balanced grain-free diet (Acana Pork and Squash formula; APS) for 26 wk. Fasted blood samples were collected prior to the start of the trial (baseline; week 0) and at weeks 13 and 26 for analyses of blood chemistry, hematology, plasma amino acids, and whole blood taurine. Urine was collected by free catch at weeks 0 and 26 for taurine and creatinine analyses. Fresh fecal samples were collected at weeks 0 and 26 for bile acid analyses. Data were analyzed using the GLIMMIX procedure with repeated measures in SAS (v. 9.4). Plasma His, Met, Trp, and taurine and whole blood taurine concentrations increased over the course of the study (P < 0.05). Urinary taurine to creatinine ratio was not affected by diet (P > 0.05). Fecal bile acid excretion increased after 26 wk of feeding APS to dogs. Despite the higher fecal excretion of bile acids, plasma and whole blood taurine increased over the 26-wk feeding study. These data suggest that feeding APS, a grain-free diet, over a 26-wk period improved taurine status in Labrador Retrievers and is not the basis for the incidence of DCM for dogs fed APS. Other factors that may contribute to the etiology of DCM should be explored.

The Effects of Nutrition on the Gastrointestinal Microbiome of Cats and Dogs: Impact on Health and Disease

The gastrointestinal (GI) microbiome of cats and dogs is increasingly recognized as a metabolically active organ inextricably linked to pet health. Food serves as a substrate for the GI microbiome of cats and dogs and plays a significant role in defining the composition and metabolism of the GI microbiome. The microbiome, in turn, facilitates the host's nutrient digestion and the production of postbiotics, which are bacterially derived compounds that can influence pet health. Consequently, pet owners have a role in shaping the microbiome of cats and dogs through the food they choose to provide. Yet, a clear understanding of the impact these food choices have on the microbiome, and thus on the overall health of the pet, is lacking. Pet foods are formulated to contain the typical nutritional building blocks of carbohydrates, proteins, and fats, but increasingly include microbiome-targeted ingredients, such as prebiotics and probiotics. Each of these categories, as well as their relative proportions in food, can affect the composition and/or function of the microbiome. Accumulating evidence suggests that dietary components may impact not only GI disease, but also allergies, oral health, weight management, diabetes, and kidney disease through changes in the GI microbiome. Until recently, the focus of microbiome research was to characterize alterations in microbiome composition in disease states, while less research effort has been devoted to understanding how changes in nutrition can influence pet health by modifying the microbiome function. This review summarizes the impact of pet food nutritional components on the composition and function of the microbiome and examines evidence for the role of nutrition in impacting host health through the microbiome in a variety of disease states. Understanding how nutrition can modulate GI microbiome composition and function may reveal new avenues for enhancing the health and resilience of cats and dogs.

Effects of Brewer's spent grain and carrot pomace on digestibility, fecal microbiota, and fecal and urinary metabolites in dogs fed low- or high-protein diets1

Brewer's spent grain (BSG) and carrot pomace (CAP) were used as fiber sources in low- or high-protein diets in dogs. Ten adult Beagles were involved in 5 feeding periods of 19 d in a cross-over design. Experimental diets contained 7.5% of total dietary fiber (TDF) from BSG or CAP and 20% or 40% of crude protein in dry matter. A diet with 3.5% TDF from both fiber sources and 20% crude protein was used as reference. Fecal dry matter was 27% higher for diets with BSG compared to CAP (P < 0.001). Apparent fecal digestibility of crude protein was 7% to 11% higher in diets with 40% protein concentration (P < 0.001), while apparent digestibility of crude fat was 2% to 3% higher for diets with CAP (P < 0.001). Carrot pomace increased the apparent fecal digestibility of TDF, phosphorus, and magnesium (P < 0.001), while 40% protein diets had a positive impact on TDF and sodium and a negative effect on magnesium apparent fecal digestibility (P < 0.001). Inclusion of CAP increased fecal short-chain fatty acids (P = 0.010), mainly acetate (P = 0.001). i-butyrate (P = 0.001), i-valerate (P = 0.002), biogenic amines (P < 0.001), and ammonium (P < 0.001) increased with higher dietary protein levels. Diet-induced changes in the fecal microbiome were moderate. Relative abundance of Bifidobacteriales was higher for the low-protein diets (P = 0.001). To conclude, BSG and CAP can be used as fiber sources in canine diets and are well tolerated even at higher inclusion rates, the effect on microbial protein fermentation seems to be limited compared to the dietary protein level.

Effect of a "diluted" diet containing 10% lignocellulose on the gastrointestinal tract, intestinal microbiota, and excreta characteristics of dual purpose laying hens

Low performing dual purpose hens have different nutritional requirements compared to conventional hybrid hens. Lignocellulose is a low fermentable polymer, acting as a diet diluent and may influence physiological and digestive processes. This study investigated the effect of a 10% dietary lignocellulose dilution on the development of gastrointestinal organs, intestinal morphology, intestinal microbiota, and excreta characteristics of dual purpose hens. One-day-old female Lohmann Dual chicks were allocated to 12 pens and fed two different diets: A standard control diet (CON) and a treatment diet (LC), based on CON but diluted with 10% lignocellulose (ARBOCEL®). At 52 wk of age, gastrointestinal organs were extracted and weights determined. Colorectal tissue samples were chemically fixed and stained for histomorphological examinations. Cecal digesta samples were analyzed for bacterial metabolites and composition using gas chromatography, HPLC, photometry, and PCR. Excreta dry matter and viscosity was consistently assessed during the trial. LC-fed hens showed increased weights of the gizzard (P = 0.003), small (P < 0.001), and large intestine (P = 0.048) compared to hens fed CON. LC-fed hens had a larger colorectal villus area (P = 0.049), a higher mucosal enlargement factor of villi (P = 0.016) and crypts (P = 0.030) than CON-fed hens. The concentration of short-chain fatty acids (SCFAs) (P = 0.017) and ammonia (P = 0.013) was higher in CON-fed hens compared to LC-fed hens. Bacterial composition and activity was generally not affected by feeding the different diets. LC-fed hens had a higher excreta dry matter content than hens fed CON at 10 (P < 0.001), 17 (P < 0.001), and 22 (P = 0.002) wk of age. Correlation analyses revealed a negative relationship between the concentration of SCFAs in the cecum and the colorectal villus surface area (P < 0.01). In conclusion, the feeding of high levels of lignocellulose increased gastrointestinal organ weights and colorectal surface area in dual purpose laying hens. A higher intestinal surface area in combination with lower concentrations of SCFAs might indicate a compensatory reaction of hens fed LC enhancing the absorption of bacterial metabolites by increasing the intestinal mucosal surface.

Production of thermostable endo-1,5-α-L-arabinanase in Pichia pastoris for enzymatically releasing functional oligosaccharides from sugar beet pulp

Sugar beet pulp is an agricultural processing residue that is a rich source of the cell wall polysaccharide arabinan. Functional oligosaccharides, specifically feruloylated arabino-oligosaccharides (FAOs), can be isolated from sugar beet pulp through selective action by endo-arabinanase (glycoside hydrolase family 43). This study aimed to develop yeast (Pichia pastoris) as an efficient, eukaryotic platform to produce a thermophilic endo-1,5-α-L-arabinanase (TS-ABN) for extracting FAOs from sugar beet pulp. Recombinant TS-ABN was secreted into yeast culture medium at a yield of ~ 80 mg/L, and the protein exhibited specific enzyme activity, pH and temperature optimum, and thermostability comparable to those of the native enzyme. Treatment of sugar beet pulp with Pichia-secreted TS-ABN released FAOs recovered by hydrophobic chromatography at 1.52% (w/w). The isolated FAOs averaged seven arabinose residues per ferulic acid, and treatment of T84 human colon epithelial cells significantly increased expression of two key tight junction-related proteins-zonula occludens-1 and occludin-in a dose-dependent manner. This research establishes a biochemical platform for utilizing sugar beet pulp to produce value-added bioproducts with potential nutraceutical applications.

Synergistic Effects of Probiotics and Phytobiotics on the Intestinal Microbiota in Young Broiler Chicken

Probiotics and phytobiotics have been studied as in-feed antibiotic alternatives for decades, yet there are no studies on their possible symbiotic effects. In the present study, newly hatched chickens were fed with feeds supplemented either with host-specific Lactobacillus strains (L. agilis and L. salivarius), commercial phytobiotics, or combinations of both. After 13 days of life, crops and caecums were analyzed for bacterial composition (16S rDNA sequencing, qPCR) and activity (bacterial metabolites). Crop and caecum samples were also used to study the ex vivo survival of a broiler-derived extended-spectrum beta-lactamase (ESBL) producing Escherichia coli strain. In the crop, combinations of probiotics and phytobiotics, but not their single application, increased the dominance of lactobacilli. The single application of phytobiotics reduced the metabolite concentrations in the crop, but certain combinations synergistically upregulated the metabolites. Changes in the qualitative and quantitative composition of the caecal microbiota were less pronounced than in the crop. Acetate concentrations were significantly lower for phytobiotics or the L. agilis probiotic strain compared to the control group, but the L. salivarius probiotic showed significantly higher acetate concentrations alone or in combination with one phytobiotic. The synergistic effects on the reduction of the ex vivo survival of an ESBL producing E. coli strain in crop or caecum contents were also observed for most combinations. This study shows the beneficial synergistic effects of probiotics and phytobiotics on the intestinal bacterial composition and their metabolic activity in young broilers. The reduced survival of potentially problematic bacteria, such as ESBL-producing E. coli further indicates that combinations of probiotics and phytobiotics may lead to a more enhanced functionality than their individual supplementation.

Dietary supplementation of a fiber-prebiotic and saccharin-eugenol blend in extruded diets fed to dogs

Prebiotics and dietary fibers are nondigestible ingredients that may confer benefits to the host by selectively stimulating beneficial intestinal bacteria and microbial-derived metabolites that support gut and host health. This experiment evaluated the effects of a blend of prebiotics and dietary fibers on apparent total tract digestibility (ATTD) and fecal metabolites related to gastrointestinal health in adult dogs. Four diets containing either 5% cellulose (control; CT), 5% dietary fiber and prebiotic blend (FP), 0.02% saccharin and eugenol (SE), or 5% fiber blend plus 0.02% saccharin and eugenol (FSE) were formulated to meet or exceed the AAFCO (2017) nutritional requirements for adult dogs. Eight adult female beagles (mean age 4.2 ± 1.1 yr; mean BW = 10.8 ± 1.4 kg; mean BCS = 5.8 ± 0.6) were randomly assigned to 1 of the 4 dietary treatments using a replicated 4 × 4 Latin square design. Each experimental period consisted of 14 d (10 d of diet adaptation and 4 d of total and fresh fecal and total urine collection). All animals remained healthy throughout the study, with serum metabolites being within reference ranges for adult dogs. All diets were well accepted by the dogs, resulting in similar (P > 0.05) daily food intakes among treatments. Likewise, fecal output and scores did not differ (P > 0.05) among dietary treatments, with the latter being within the ideal range (2.5-2.9) in a 5-point scale. All diets were highly digestible and had similar (P > 0.05) ATTD of dry matter (81.6%-84.4%), organic matter (86.4%-87.3%), and crude protein (86.6%-87.3%). However, total dietary fiber (TDF) digestibility was greater for dogs fed the FSE diet (P < 0.05) in contrast with dogs fed the CT and SE diets, whereas dogs fed FP diets had intermediate TDF digestibility, but not different from all other treatments. Fecal acetate and propionate concentrations were greater (P < 0.05) for dogs fed FP and FSE diets. Fecal concentrations of isobutyrate and isovalerate were greater for dogs fed CT (P < 0.05) compared with dogs fed the other three treatments. No shifts in fecal microbial richness and diversity were observed among dietary treatments. Overall, the data suggest that dietary supplementation of fiber and prebiotic blend was well tolerated by dogs, did not cause detrimental effects on fecal quality or nutrient digestibility, and resulted in beneficial shifts in fecal metabolites that may support gut health.

Effects of high inclusion of soybean hulls on apparent total tract macronutrient digestibility, fecal quality, and fecal fermentative end-product concentrations in extruded diets of adult dogs

Soybean hulls (SBH) are a fiber-rich co-product of the soybean oil extraction process that corresponds to 8% of the soybean seed. Despite being readily available and priced competitively, SBH are underutilized in monogastric nutrition. Thus, the objective of this study was to evaluate SBH as a dietary fiber in canine diets. Four diets were formulated with either SBH, beet pulp (BP), or cellulose (CL) as the main source of dietary fiber (15% total dietary fiber [TDF]), with the control diet formulated with no supplemental fiber (NF). Animal procedures were approved by the University of Illinois Institutional Animal Care and Use Committee. Eight adult female Beagle (mean age = 4.6 ± 0.6 yr; mean BW = 12.8 ± 1.7 kg) were used in a replicated 4 × 4 Latin square design. Each period consisted of 14 d, with 10 d of diet adaptation followed by 4 d of total fecal and urine collections. At the end of each period, a blood sample was collected and analyzed for serum chemistry. Food was offered twice daily and fed to maintain body weight. Food intake (g/d) on a dry matter basis (DMB) did not differ among treatments. Fecal score was lower (P < 0.05) for dogs fed CL (2.0) in contrast with other dietary treatments (2.3), using a 5-point scale (1 = hard, dry pellets; 5 = diarrhea). Fecal as-is and DM output did not differ for dogs fed BP, CL, or SBH, and were approximately 50% greater (P < 0.05) than dogs fed NF. Apparent total tract digestibility (ATTD) of dry matter, organic matter, and gross energy were greater (P < 0.05) for dogs fed NF when compared with dogs fed BP, CL, or SBH. Dogs fed CL had greater (P < 0.05) AHF ATTD (94%) compared with all other treatments (mean = 91%). Dogs fed CL and NF had greater (P < 0.05) CP ATTD, 87% and 86%, respectively, while dogs fed SBH were intermediate (83%) and dogs fed BP were lowest (79%). Total short-chain fatty acid (SCFA) concentration was greatest in dogs fed BP (582.5 μmol/g) and SBH (479.7 μmol/g) when compared with NF and CL (267.0 and 251.1 μmol/g, respectively). Serum metabolites were within-reference ranges and dogs remained healthy throughout the study. In conclusion, SBH resulted in similar macronutrient ATTD when compared with BP and CL. Dogs fed SBH were also observed to have an increase in fecal SCFA concentration. In general, high level addition of SBH were well-utilized by the dog, resulting in no untoward effects on dog health, nutrient digestibility, or fecal characteristics.

Balance of saccharolysis and proteolysis underpins improvements in stool quality induced by adding a fiber bundle containing bound polyphenols to either hydrolyzed meat or grain-rich foods

Dietary fiber is a key component in gastrointestinal health maintenance partly due to its fermentation by the gut microbiome. The food-dependent effects of a novel fiber bundle added to hydrolyzed meat (HM) or grain-rich (GR) foods in healthy dogs (n = 16) or those with chronic enteritis/gastroenteritis (n = 16) were examined. Addition of fiber to either food improved stool quality in dogs regardless of health status; microbiome diversity of dogs with chronic enteritis/gastroenteritis became more similar to healthy dogs. The abundance of bacteria mediating beneficial saccharolytic processes (eg, Lachnospiraceae) significantly increased on addition of fiber to the GR food, while those mediating detrimental proteolytic catabolism (eg, Desulfovibrionaceae) significantly decreased. Fiber addition to the HM food led to significant changes in saccharolytic/proteolytic bacteria. Higher levels of free saccharides in feces upon fiber addition to either food indicated increased saccharolysis. Fiber addition to the GR food decreased levels of fecal free amino acids, indicating decreased proteolysis. Addition of fiber decreased fecal pH for both foods but likely by different mechanisms: addition of fiber to the HM food led to increased straight-chain short-chain fatty acids (SCFAs) and no significant change in proteolytic branched-chain SFCAs, while in the GR food, fiber mainly led to decreased proteolytic branched-chain SFCAs. Other postbiotics related to intestinal health were consistently altered when fiber was added to either food. Plant-derived bioactive molecules were enriched in feces from dogs fed either food with added fiber, which could account for the observed modulation of the canine gut microbiome and shifts in metabolic capacity.

Does Modification of the Large Intestinal Microbiome Contribute to the Anti-Inflammatory Activity of Fermentable Fiber?

Fiber is an inadequately understood and insufficiently consumed nutrient. This review examines the possible causal relation between fiber-induced microbiome changes and the anti-inflammatory activity of fiber. To demonstrate the dominant role of fermentable plant fiber in shaping the intestinal microbiome, animal and human fiber-feeding studies are reviewed. Using culture-, PCR-, and sequencing-based microbial analyses, a higher prevalence of Bifidobacterium and Lactobacillus genera was observed from the feeding of different types of fermentable fiber. This finding was reported in studies performed on several host species including human. Health conditions and medications that are linked to intestinal microbial alterations likely also change the nutrient environment of the large intestine. The unique gene clusters of Bifidobacterium and Lactobacillus that enable the catabolism of plant glycans and the ability of Bifidobacterium and Lactobacillus to reduce the colonization of proteobacteria probably contribute to their prevalence in a fiber-rich intestinal environment. The fiber-induced microbiome changes could contribute to the anti-inflammatory activity of fiber. Although most studies did not measure fecal microbial density or total daily fecal microbial output (colon microbial load), limited evidence suggests that the increase in intestinal commensal microbial load plays an important role in the anti-inflammatory activity of fiber. Various probiotic supplements, including Bifidobacterium and Lactobacillus, showed anti-inflammatory activity only in the presence of fiber, which promoted microbial growth as indicated by increasing plasma short-chain fatty acids. Probiotics alone or pure fiber administered under sterile conditions showed no anti-inflammatory activity. The potential mechanisms that could mediate the anti-inflammatory effect of common microbial metabolites are reviewed, but more in vivo trials are needed. Future studies including simultaneous microbial composition and load measurements are also important.