Effects of a Saccharomyces cerevisiae fermentation product on fecal characteristics, metabolite concentrations, and microbiota populations of dogs undergoing transport stress.

Previously, a Saccharomyces cerevisiae fermentation product (SCFP) positively altered fecal microbiota, fecal metabolites, and immune cell function of adult dogs. Our objective was to determine the fecal characteristics, microbiota, and metabolites of SCFP-supplemented dogs subjected to transport stress. All procedures were approved by the Four Rivers Kennel IACUC prior to experimentation. Thirty-six adult dogs (18 male, 18 female; age: 7.1 ± 0.77 yr; body weight: 28.97 ± 3.67 kg) were randomly assigned to be controls or receive SCFP supplementation (250 mg/dog/d) (N = 18/group) for 11 wk. At that time, fresh fecal samples were collected before and after transport in a hunting dog trailer with individual kennels. The trailer was driven 40 miles round trip for about 45 min. Fecal microbiota data were evaluated using Quantitative Insights Into Microbial Ecology 2, while all other data were analyzed using the Mixed Models procedure of Statistical Analysis System. Effects of treatment, transport, and treatment × transport were tested, with P < 0.05 being considered significant. Transport stress increased fecal indole concentrations and relative abundances of fecal Actinobacteria, Collinsella, Slackia, Ruminococcus, and Eubacterium. In contrast, relative abundances of fecal Fusobacteria, Streptococcus, and Fusobacterium were reduced by transport. Fecal characteristics, metabolites, and bacterial alpha and beta diversity measures were not affected by diet alone. Several diet × transport interactions were significant, however. Following transport, relative abundance of fecal Turicibacter increased in SCFP-supplemented dogs, but decreased in controls. Following transport, relative abundances of fecal Proteobacteria, Bacteroidetes, Prevotella, and Sutterella increased in controls, but not in SCFP-supplemented dogs. In contrast, relative abundances of fecal Firmicutes, Clostridium, Faecalibacterium, and Allobaculum increased and fecal Parabacteroides and Phascolarctobacterium decreased after transport stress in SCFP-supplemented dogs, but not in controls. Our data demonstrate that both transport stress and SCFP alter fecal microbiota in dogs, with transport being the primary cause for shifts. SCFP supplementation may provide benefits to dogs undergoing transport stress, but more research is necessary to determine proper dosages. More research is also necessary to determine if and how transport stress impacts gastrointestinal microbiota and other indicators of health.

The objective of this study was to determine the fecal characteristics, microbiota, and metabolites of dogs supplemented with a Saccharomyces cerevisiae fermentation product (SCFP) and subjected to transport stress. Thirty-six adult dogs were randomly assigned to a control diet or an SCFP-supplemented diet (N = 18 per group) and fed for 11 wk. At that time, a transport stress challenge was conducted. Fresh fecal samples were collected for measurement of general characteristics, microbiota, and metabolites before and after transport stress. Transport stress increased fecal indoles and Actinobacteria, Collinsella, Slackia, Ruminococcus, and Eubacterium populations and decreased fecal Fusobacteria, Streptococcus, and Fusobacterium populations. Fecal characteristics, metabolites, and bacterial alpha and beta diversity measures were not affected by diet alone, but several diet × transport interactions were significant. Following transport, fecal Turicibacter increased in SCFP-supplemented dogs, but decreased in controls. Following transport, fecal Proteobacteria, Bacteroidetes, Prevotella, and Sutterella increased in controls, but not in SCFP-supplemented dogs. Fecal Firmicutes, Clostridium, Faecalibacterium, and Allobaculum increased and fecal Parabacteroides and Phascolarctobacterium decreased after transport stress in SCFP-supplemented dogs, but not in controls. Our data demonstrate that both transport stress and SCFP alter fecal microbiota in dogs. SCFP supplementation may provide benefits to dogs undergoing stress, but proper dosages need to be determined.

Evaluation of high-protein diets differing in protein source in healthy adult dogs.

Given the dynamic market for protein-based ingredients in the pet food industry, demand continues to increase for both plant- and animal-based options. Protein sources contain different amino acid (AA) profiles and vary in digestibility, affecting protein quality. The objective of this study was to evaluate the apparent total tract digestibility (ATTD) of canine diets differing in protein source and test their effects on serum metabolites and fecal characteristics, metabolites, and microbiota of healthy adult dogs consuming them. Four extruded diets were formulated to be isonitrogenous and meet the nutrient needs for adult dogs at maintenance, with the primary difference being protein source: 1) fresh deboned, dried, and spray-dried chicken (DC), 2) chicken by-product meal (CBPM), 3) wheat gluten meal (WGM), and 4) corn gluten meal (CGM). Twelve adult spayed female beagles (body weight [BW] = 9.9 ± 1.0 kg; age = 6.3 ± 1.1 yr) were used in a replicated 4 × 4 Latin square design (n = 12/treatment). Each period consisted of a 22-d adaptation phase, 5 d for fecal collection, and 1 d for blood collection. Fecal microbiota data were analyzed using QIIME 2.2020.8. All other data were analyzed using the Mixed Models procedure of SAS version 9.4. Fecal scores were higher (P < 0.05; looser stools) in dogs fed DC or CBPM than those fed WGM or CGM, but all remained within an appropriate range. Dry matter ATTD was lower (P < 0.05) in dogs fed CBPM or CGM than those fed DC or WGM. Crude protein ATTD was lower (P < 0.05) in dogs fed DC or CGM than those fed WGM. Dogs fed CBPM had lower (P < 0.05) organic matter, crude protein, and energy ATTD than those fed the other diets. Fecal indole was higher (P < 0.05) in dogs fed CBPM than those fed WGM. Fecal short-chain fatty acids were higher (P < 0.05) in dogs fed DC than those fed CGM. Fecal branched-chain fatty acids were higher (P < 0.05) in dogs fed DC or CBPM than those fed WGM. Fecal ammonia was higher (P < 0.05) in dogs fed DC or CBPM than those fed WGM or CGM. The relative abundances of three bacterial phyla and nine bacterial genera were shifted among treatment groups (P < 0.05). Considering AA profiles and digestibility data, the DC diet protein sources provided the highest quality protein without additional AA supplementation, but the animal-based protein diets resulted in higher fecal proteolytic metabolites. Further studies evaluating moderate dietary protein concentrations are needed to better compare plant- and animal-based protein sources.

Pet food trends are constantly changing. Because consumers are often focused on dietary proteins, with ingredient sources, dietary inclusion levels, and processing methods being important, they are a popular research topic. Protein sources contain different amino acid (AA) profiles and vary in digestibility, affecting protein quality. Our objective was to evaluate the apparent total tract digestibility of canine diets differing in protein source and test their effects on serum metabolites and fecal characteristics, metabolites, and microbiota of healthy adult dogs. Test diets were formulated to be similar nutritionally, but differed in protein source: fresh deboned, dried, and spray-dried chicken (DC), chicken by-product meal (CBPM), wheat gluten meal (WGM), and corn gluten meal (CGM). Fecal scores were higher in dogs fed chicken-based diets, but remained within an appropriate range. Dogs fed CBPM had lower nutrient and energy digestibilities than those fed the other diets, with protein digestibility also being lower in dogs fed DC or CGM than those fed WGM. Fecal metabolites and microbiota were shifted among diets, with animal-based protein diets increasing fecal protein metabolites. All diets were complete and balanced and performed well. When considering AA profiles and digestibility, however, the DC diet provided the highest protein quality.

Effects of a milk oligosaccharide biosimilar on fecal characteristics, microbiota, and bile acid, calprotectin, and immunoglobulin concentrations of healthy adult dogs treated with metronidazole.

In recent dog and cat experiments, a novel milk oligosaccharide biosimilar (GNU100) positively modulated fecal microbiota and metabolite profiles, suggesting benefits to gastrointestinal health. The objective of this study was to investigate the effects of GNU100 on the fecal characteristics, microbiota, and bile acid (BA) concentrations of healthy adult dogs treated with antibiotics. Twelve healthy adult female dogs (mean age: 3.74 ± 2.4 yr) were used in an 8-wk crossover design study (dogs underwent both treatments). All dogs were fed a control diet during a 2-wk baseline, then randomly allotted to 1 of 2 treatments (diet only or diet + 1% GNU100) for another 6 wk. From weeks 2 to 4, dogs were orally administered metronidazole (20 mg/kg BW) twice daily. Fecal scores were recorded daily and fresh fecal samples were collected at weeks 2, 4, 5, 6, and 8 for measurement of pH, dry matter, microbiota populations, and BA, immunoglobulin A, and calprotectin concentrations. On weeks 0, 4, and 8, blood samples were collected for serum chemistry and hematology analysis. All data were analyzed as repeated measures using the Mixed Models procedure of SAS version 9.4, with significance considered P < 0.05. Metronidazole increased (P < 0.0001) fecal scores (looser stools) and modified (P < 0.05) fecal microbiota and BA profiles. Using qPCR, metronidazole reduced fecal Blautia, Fusobacterium, Turicibacter, Clostridium hiranonis, and Faecalibacterium abundances, and increased fecal Streptococcus and Escherichia coli abundances. DNA sequencing analysis demonstrated that metronidazole reduced microbial alpha diversity and influenced the relative abundance of 20 bacterial genera and families. Metronidazole also increased primary BA and reduced secondary BA concentrations. Most antibiotic-induced changes returned to baseline by week 8. Fecal scores were more stable (P = 0.01) in GNU100-fed dogs than controls after antibiotic administration. GNU100 also influenced fecal microbiota and BA profiles, reducing (P < 0.05) the influence of metronidazole on microbial alpha diversity and returning some fecal microbiota and secondary BA to baseline levels at a quicker (P < 0.05) rate than controls. In conclusion, our results suggest that GNU100 supplementation provides benefits to dogs treated with antibiotics, providing more stable fecal scores, maintaining microbial diversity, and allowing for quicker recovery of microbiota and secondary BA profiles which play an essential role in gut health.

Our objective was to test the effects of a novel milk oligosaccharide biosimilar (GNU100) on the fecal characteristics, microbiota, and bile acid (BA) concentrations of healthy adult dogs treated with antibiotics. Dogs were fed a control diet during a 2-wk baseline, then randomly allotted to 1 of 2 treatments (diet only or diet + 1% GNU100) for another 6 wk. From weeks 2 to 4, dogs were given an oral antibiotic. Fecal scores were recorded and fresh fecal samples were collected over time to assess fecal characteristics, microbiota populations, and BA concentrations. The antibiotic was shown to increase fecal scores (looser stools) and modify fecal microbiota populations (altered diversity and ~20 bacterial genera and families) and BA profiles (increased primary and reduced secondary BA). Most antibiotic-induced changes returned to baseline by week 8. In dogs fed GNU100, fecal scores were more stable and changes to microbial diversity were lower than controls after antibiotic administration. Fecal microbiota and secondary BA of GNU100-fed dogs also returned to baseline levels at a quicker rate than controls. These results suggest that GNU100 provides benefits to dogs given antibiotics, providing more stable fecal scores, maintaining microbial diversity, and allowing for quicker recovery of microbiota and BA profiles.

Longitudinal fecal microbiome and metabolite data demonstrate rapid shifts and subsequent stabilization after an abrupt dietary change in healthy adult dogs.

BACKGROUND: Diet has a large influence on gut microbiota diversity and function. Although previous studies have investigated the effect of dietary interventions on the gut microbiome, longitudinal changes in the gut microbiome, microbial functions, and metabolite profiles post dietary interventions have been underexplored. How long these outcomes require to reach a steady-state, how they relate to one another, and their impact on host physiological changes are largely unknown. To address these unknowns, we collected longitudinal fecal samples following an abrupt dietary change in healthy adult beagles (n = 12, age: 5.16 ± 0.87 year, BW: 13.37 ± 0.68 kg) using a crossover design. All dogs were fed a kibble diet (control) from d1-14, and then fed that same diet supplemented with fiber (HFD) or a protein-rich canned diet (CD) from d15-27. Fresh fecal samples were collected on d13, 16, 20, 24, and 27 for metabolite and microbiome assessment. Fecal microbial diversity and composition, metabolite profiles, and microbial functions dramatically diverged and stabilized within a few days (2 d for metabolites; 6 d for microbiota) after dietary interventions. Fecal acetate, propionate, and total short-chain fatty acids increased after change to HFD, while fecal isobutyrate, isovalerate, total branched-chain fatty acids, phenol, and indole increased after dogs consumed CD. Relative abundance of ~ 100 bacterial species mainly belonging to the Firmicutes, Proteobacteria, and Actinobacteria phyla increased in HFD. These shifts in gut microbiome diversity and composition were accompanied by functional changes. Transition to HFD led to increases in the relative abundance of KEGG orthology (KO) terms related to starch and sucrose metabolism, fatty acid biosynthesis, and amino sugar and nucleotide sugar metabolism, while transition to CD resulted in increased relative abundance of KO terms pertaining to inositol phosphate metabolism and sulfur metabolism. Significant associations among fecal microbial taxa, KO terms, and metabolites were observed, allowing for high-accuracy prediction of diet group by random forest analysis. CONCLUSIONS: Longitudinal sampling and a multi-modal approach to characterizing the gastrointestinal environment allowed us to demonstrate how drastically and quickly dietary changes impact the fecal microbiome and metabolite profiles of dogs following an abrupt dietary change and identify key microbe-metabolite relationships that allowed for treatment prediction.

Impact of administration route on nanocarrier biodistribution in a murine colitis model.

The incidence of inflammatory bowel disease (IBD) is increasing worldwide. Although current diagnostic and disease monitoring tests for IBD sensitively detect gut inflammation, they lack the molecular and cellular specificity of positron emission tomography (PET). In this proof-of-concept study, we use a radiolabeled macrophage-targeted nanocarrier probe (64Cu-NOTA-D500) administered by oral, enema, and intraperitoneal routes to evaluate the delivery route dependence of biodistribution across healthy and diseased tissues in a murine model of dextran sodium sulfate (DSS)-induced colitis. High inter-subject variability of probe uptake in intestinal tissue was reduced by normalization to uptake in liver or total intestines. Differences in normalized uptake between healthy and DSS colitis animal intestines were highest for oral and IP routes. Differences in absolute liver uptake reflected a possible secondary diagnostic metric of IBD pathology. These results should inform the preclinical development of inflammation-targeted contrast agents for IBD and related gut disorders to improve diagnostic accuracy.

Effects of incremental exercise and dietary tryptophan supplementation on the amino acid metabolism, serotonin status, stool quality, fecal metabolites, and body composition of mid-distance training sled dogs.

Exercise improves the health of dogs; however, the extreme exertion experienced by sled dogs may lead to variable metabolic and fecal characteristics. Nutritional interventions, such as dietary tryptophan (Trp), may reduce the prevalence of these exercise-induced disturbances. Sporting diets tend to have high crude protein concentrations in contrast to adult maintenance diets and this results in less Trp relative to other amino acids (AA). Therefore, sporting dogs represent an ideal cohort to assess the effects of supplemental Trp. The objective was to evaluate the effects of supplemental dietary Trp and an incremental training regimen on AA and serotonin status, fecal scores and metabolites, and body composition in client-owned Siberian huskies. Sixteen dogs (nine females and seven males) were used, with a mean age of 4.8 ± 2.5 yr and body weight (BW) of 24.3 ± 4.3 kg. Dogs were blocked for sex, age, and BW and randomly allocated into two groups with eight fed a dry extruded control diet (Ctl) and eight fed Ctl supplemented with Trp to reach a Trp:large-neutral AA (LNAA) ratio of 0.075:1 (treatment, Trt). The exercise regimen was designed to increase in distance each week, but weather played a role in setting the daily distance. Each week BW was recorded and food allotments were adjusted to maintain initial BW. Pre and post-exercise blood samples were taken every 3 wk, dogs then received a meal followed by 1, 2, and 4 h post meal blood collections (serum AA, serotonin). Stool collection and scoring occurred each week and body composition was measured on weeks -1 and 11. Serotonin, AA, fecal metabolite, and body composition data were analyzed using PROC MIXED of SAS with dog as a random effect and week and Trt as fixed effects. Stool score data were analyzed using PROC FREQ to compare stool score and Trt, and PROC CORR was used to analyze associations between fecal score, temperature, humidity, and run distance. Dogs on Trt had greater fasted Trp compared with baseline, greater post-meal Trp and serotonin compared with baseline, greater post-meal Trp compared with fasted, and greater post-meal Trp and serotonin compared with Ctl (P < 0.05). Fecal data indicated that Trp improved stool scores (P < 0.05) yet had no effect on fecal metabolites. An overall increase in lean and decrease in fat mass was found (P < 0.05), but Trt had no effect on body composition. Optimization of the dietary Trp:LNAA ratio may help to improve GI health without compromising performance in actively training sled dogs.

Perspective: Physiologic Importance of Short-Chain Fatty Acids from Nondigestible Carbohydrate Fermentation.

In recent years, it has become increasingly obvious that dietary fiber or nondigestible carbohydrate (NDC) consumption is critical for maintaining optimal health and managing symptoms of metabolic disease. In accordance with this, the US FDA released its first official definition of dietary fiber in 2016 for regulation of Nutrition and Supplement Facts labels. Included in this definition is the requirement of an isolated or synthetic NDC to produce an accepted physiologic health benefit, such as improved laxation or reduced fasting cholesterol concentrations, upon consumption. Even though NDC fermentation and production of short-chain fatty acids elicit many physiologic effects, including serving as a source of energy for colonocytes, curbing glycemic response and satiety, promoting weight loss, enhancing mineral absorption, reducing systemic inflammation, and improving intestinal health, the process of fermentation is not considered a physiologic endpoint. Instead, expensive and laborious clinical trials must be conducted and an accepted physiologic benefit observed. In this review, we discuss the physiologic importance of NDC fermentation through extensive examination of clinical evidence and propose that the degree of fermentability of an NDC, rather than the endpoints of a clinical trial, may be appropriate for classifying it as a dietary fiber.

Effects of a Saccharomyces cerevisiae fermentation product on fecal characteristics, nutrient digestibility, fecal fermentative end-products, fecal microbial populations, immune function, and diet palatability in adult dogs1.

Yeast products may serve as functional ingredients due to their benefits on host health but vary greatly in source, composition, and functionality, justifying research in host species of interest. In this study, a Saccharomyces cerevisiae fermentation product (SCFP) was investigated as a dietary supplement for adult dogs. Adult female beagles (n = 12; mean age = 3.3 ± 0.8 yr; mean BW = 10.3 ± 0.68 kg) were fed the same diet, but supplemented with three levels of SCFP (125, 250, and 500 mg/d) or a placebo (sucrose) via gelatin capsules in a replicated 4 × 4 Latin square design. Fecal samples for nutrient digestibility, fecal characteristics and microbial populations as well as blood samples for immune indices were collected after a 21-d adaptation phase in each period. A separate palatability test was conducted to examine palatability of an SCFP-containing diet (0.2% of diet). All data, except for palatability data, were analyzed by Mixed Models procedure of SAS (version 9.4). A paired t-test was conducted to analyze data from the palatability test. Supplementation of SCFP did not affect total tract apparent macronutrient and energy digestibilities or fecal characteristics. Fecal phenol and total phenol + indole concentrations decreased linearly with SCFP dosage (P < 0.05). Relative abundance of Bifidobacterium was greater (P < 0.05), while Fusobacterium was lower (P < 0.05) in SCFP-supplemented dogs. Total white blood cell counts were decreased by SCFP (P < 0.05). The percentage of natural killer cells and antigen-presenting cells were not altered by SCFP. However, when comparing control vs. all SCFP treatments, SCFP-supplemented dogs had greater (P < 0.05) major histocompatibility complex class II presenting B cell and monocyte populations than control dogs. IFN-γ secreting helper and cytotoxic T cells increased linearly with SCFP consumption (P < 0.05). Immune cells derived from SCFP-supplemented dogs produced less (P < 0.05) TNF-α than those from control dogs when cells were stimulated with agonists of toll-like receptors 2, 3, 4, and 7/8. A linear increase (P < 0.05) in serum IgE with SCFP dosage was noted. In the palatability test, a 1.9:1 consumption ratio was observed for the SCFP-containing diet vs. control diet, demonstrating a preference (P < 0.05) for SCFP. Results of this study suggest that SCFP supplementation may be beneficial to adult dogs by positively altering gut microbiota, enhancing immune capacity and reducing inflammation.

Longitudinal changes in blood metabolites, amino acid profile, and oxidative stress markers in American Foxhounds fed a nutrient-fortified diet.

The objective of the present study was to evaluate the changes in blood metabolites, AA profile, and oxidative stress markers in American Foxhound dogs fed a nutrient-fortified endurance diet while undergoing unstructured endurance exercise over several months. Thirty-six adult American Foxhound dogs (mean age: 4.5, range 2 to 10 yr and mean BW: 34.7, range: 23.1 to 46.9 kg) were selected to participate in the study. Prior to the study, all dogs consumed a commercial diet for 16 wk. After collecting baseline blood samples, dogs were assigned to a standard commercial performance diet (control) or a nutrient-fortified dog food (test). Dogs were balanced by gender, age, body weight, and athletic performance between diets. During the study, dogs underwent 78 bouts of exercise, with approximately 22 km/bout. Blood samples were collected after 40, 75, 138, and 201 d on study (October 2012 to March 2013). All blood metabolites were similar at baseline and serum chemistry profile remained within normal ranges throughout the study. Over time, plasma taurine and vitamin E concentrations decreased (P < 0.05) in dogs fed the control diet but were maintained or increased (P < 0.05) in dogs fed the treatment diet. Also, plasma creatinine and triglycerides were lower (P < 0.05) and blood phosphorus and alkaline phosphatase were higher (P < 0.05) in dogs fed the treatment diet. Vitamin E and taurine status of dogs appear to be affected by extended endurance exercise. These data suggest dogs undergoing endurance exercise may benefit from supplementation of vitamin E and taurine to minimize oxidation and maintain taurine status.

Soy Improves Cardiometabolic Health and Cecal Microbiota in Female Low-Fit Rats.

Phytoestrogen-rich soy is known to ameliorate menopause-associated obesity and metabolic dysfunction for reasons that are unclear. The gut microbiota have been linked with the development of obesity and metabolic dysfunction. We aimed to determine the impact of soy on cardiometabolic health, adipose tissue inflammation, and the cecal microbiota in ovariectomized (OVX) rats bred for low-running capacity (LCR), a model that has been previously shown to mimic human menopause compared to sham-operated (SHM) intact control LCR rats. In this study, soy consumption, without affecting energy intake or physical activity, significantly improved insulin sensitivity and body composition of OVX rats bred for low-running capacity. Furthermore, soy significantly improved blood lipid profile, adipose tissue inflammation, and aortic stiffness of LCR rats. Compared to a soy-free control diet, soy significantly shifted the cecal microbial community of LCR rats, resulting in a lower Firmicutes:Bacteroidetes ratio. Correlations among metabolic parameters and cecal bacterial taxa identified in this study suggest that taxa Prevotella, Dorea, and Phascolarctobacterium may be taxa of interest. Our results suggest that dietary soy ameliorates adiposity, insulin sensitivity, adipose tissue inflammation, and arterial stiffness and exerts a beneficial shift in gut microbial communities in a rat model that mimics human menopause.

Ontogenetic Characterization of the Intestinal Microbiota of Channel Catfish through 16S rRNA Gene Sequencing Reveals Insights on Temporal Shifts and the Influence of Environmental Microbes.

Aquaculture recently overtook capture fisheries as the largest producer of food fish, but to continue increasing fish production the industry is in search of better methods of improving fish health and growth. Pre- and probiotic supplementation has gained attention as a means of solving these issues, however, for such approaches to be successful, we must first gain a more holistic understanding of the factors influencing the microbial communities present in the intestines of fish. In this study, we characterize the bacterial communities associated with the digestive tract of a highly valuable U.S. aquaculture species, channel catfish Ictalurus punctatus, over the first 193 days of life to evaluate temporal changes that may occur throughout ontogenetic development of the host. Intestinal microbiota were surveyed with high-throughput DNA sequencing of 16S rRNA V4 gene amplicons derived from fish at 3, 65, 125, and 193 days post hatch (dph), while also characterizing the environmental microbes derived from the water supply and the administered diets. Microbial communities inhabiting the intestines of catfish early in life were dynamic, with significant shifts occurring up to 125 dph when the microbiota somewhat stabilized, as shifts were less apparent between 125 to 193 dph. Bacterial phyla present in the gut of catfish throughout ontogeny include Bacteroidetes, Firmicutes, Fusobacteria, and Proteobacteria; with the species Cetobacterium somerae and Plesiomonas shigelloides showing the highest abundance in the catfish microbiota after 3 dph. Comparisons of the gut microbiota to the environmental microbes reveals that the fish gut is maintained as a niche habitat, separate from the overall microbial communities present in diets and water-supply. Although, there is also evidence that the environmental microbiota serves as an inoculum to the fish gut. Our results have implications for future research related to channel catfish biology and culture, and increase our understanding of ontogenetic effects on the microbiota of teleost fish.

Agave Inulin Supplementation Affects the Fecal Microbiota of Healthy Adults Participating in a Randomized, Double-Blind, Placebo-Controlled, Crossover Trial.

BACKGROUND: Prebiotics resist digestion, providing fermentable substrates for select gastrointestinal bacteria associated with health and well-being. Agave inulin differs from other inulin type fibers in chemical structure and botanical origin. Preclinical animal research suggests these differences affect bacterial utilization and physiologic outcomes. Thus, research is needed to determine whether these effects translate to healthy adults. OBJECTIVE: We evaluated agave inulin utilization by the gastrointestinal microbiota by measuring fecal fermentative end products and bacterial taxa. METHODS: A randomized, double-blind, placebo-controlled, 3-period, crossover trial was undertaken in healthy adults (n = 29). Participants consumed 0, 5.0, or 7.5 g agave inulin/d for 21 d with 7-d washouts between periods. Participants recorded daily dietary intake; fecal samples were collected during days 16-20 of each period and were subjected to fermentative end product analysis and 16S Illumina sequencing. RESULTS: Fecal Actinobacteria and Bifidobacterium were enriched (P < 0.001) 3- and 4-fold after 5.0 and 7.5 g agave inulin/d, respectively, compared with control. Desulfovibrio were depleted 40% with agave inulin compared with control. Agave inulin tended (P < 0.07) to reduce fecal 4-methyphenol and pH. Bivariate correlations revealed a positive association between intakes of agave inulin (g/kcal) and Bifidobacterium (r = 0.41, P < 0.001). Total dietary fiber intake (total fiber plus 0, 5.0, or 7.5 g agave inulin/d) per kilocalorie was positively associated with fecal butyrate (r = 0.30, P = 0.005), tended to be positively associated with Bifidobacterium (r = 0.19, P = 0.08), and was negatively correlated with Desulfovibrio abundance (r = -0.31, P = 0.004). CONCLUSIONS: Agave inulin supplementation shifted the gastrointestinal microbiota composition and activity in healthy adults. Further investigation is warranted to determine whether the observed changes translate into health benefits in human populations. This trial was registered at clinicaltrials.gov as NCT01925560.

Fiber supplementation influences phylogenetic structure and functional capacity of the human intestinal microbiome: follow-up of a randomized controlled trial.

BACKGROUND: In our published randomized, double-blind, placebo-controlled, 3-period crossover trial, healthy adult men (n = 21) consumed bars containing no supplemental fiber (placebo; NFC), polydextrose (21 g/d), and soluble corn fiber (SCF; 21 g/d) for 21 d each. Fecal specimens were collected between days 16 and 21 for fermentative end-product analysis and 16S ribosomal RNA bacterial gene amplification for bacterial taxa identification. Fiber supplementation decreased fecal putrefaction compounds and shifted abundances of several bacterial taxa. OBJECTIVE: The objective was to perform whole-genome shotgun 454 pyrosequencing on the same fecal specimens collected in that clinical trial to obtain comprehensive fecal bacterial genome sequencing coverage and explore the full range of bacterial genetic information in the fecal microbiome, thereby using a systematic approach to study the impact of dietary fiber supplementation on fecal metabolites, bacterial taxa, and bacterial metagenomes. DESIGN: Fecal samples were subjected to whole-genome shotgun 454 pyrosequencing to identify both fecal bacterial populations present and their functional genetic capacity. RESULTS: Whole-genome shotgun sequencing results revealed that fiber consumption shifted the Bacteroidetes:Firmicutes ratio, increasing the relative abundance of Bacteroidetes 12 ± 2% and 13 ± 2% with polydextrose and SCF, respectively, compared with NFC. Bivariate correlations showed a positive correlation between the Bacteroidetes:Firmicutes ratio and total dietary fiber intake but not body mass index. Principal coordinates analysis of Bray-Curtis distances indicated that bacterial gene composition was more similar in participants consuming fibers (polydextrose and SCF combined) in comparison with NFC. Shifts in bacterial gene abundances after polydextrose and SCF supplementation included genes associated with carbohydrate, amino acid, and lipid metabolism, as well as metabolism of cofactors and vitamins. CONCLUSION: This study conveys novel information about the impact of dietary fiber supplementation on the phylogenetic structure and functional capacity of the fecal microbiome of healthy adults.

Modulation of the faecal microbiome of healthy adult dogs by inclusion of potato fibre in the diet.

Inclusion of fermentable fibres in the diet can have an impact on the hindgut microbiome and provide numerous health benefits to the host. Potato fibre (PF), a co-product of potato starch isolation, has a favourable chemical composition of pectins, resistant and digestible starch, cellulose, and hemicelluloses. The objective of the present study was to evaluate the effect of increasing dietary PF concentrations on the faecal microbiome of healthy adult dogs. Fresh faecal samples were collected from ten female dogs with hound bloodlines (6·13 (SEM 0·17) years; 22·0 (SEM 2·1) kg) fed five test diets containing graded concentrations of PF (0, 1·5, 3, 4·5 or 6% as-fed; Roquette Frères) in a replicated 5 × 5 Latin square design. Extraction of DNA was followed by amplification of the V4-V6 variable region of the 16S rRNA gene using barcoded primers. Sequences were classified into taxonomic levels using Basic Local Alignment Search Tool (BLASTn) against a curated GreenGenes database. Inclusion of PF increased (P< 0·05) the faecal proportions of Firmicutes, while those of Fusobacteria decreased (P< 0·05). Similar shifts were observed at the genus level and were confirmed by quantitative PCR (qPCR) analysis. With increasing concentrations of PF, faecal proportions of Faecalibacterium increased (P< 0·05). Post hoc Pearson's correlation analysis showed positive (P< 0·05) correlations with Bifidobacterium spp. and butyrate production and Lactobacillus spp. concentrations. Overall, increases in the proportion of Faecalibacterium (not Lactobacillus/Bifidobacterium, as confirmed by qPCR analysis) and faecal SCFA concentrations with increasing dietary PF concentrations suggest that PF is a possible prebiotic fibre.

Effects of a synbiotic on fecal quality, short-chain fatty acid concentrations, and the microbiome of healthy sled dogs.

BACKGROUND: Sled dogs commonly suffer from diarrhea. Although multiple etiologies exist there are limited field studies using synbiotics as a supplement to prevent or treat diarrhea. The objective of this study was to examine alterations in fecal quality, short-chain fatty acids (SCFA), and the fecal microbiome in two groups of training sled dogs fed a synbiotic or microcrystalline cellulose placebo. Twenty clinically healthy training sled dogs randomized into two cohorts (9 synbiotic-fed, 8 placebo-fed) for a 6 week prospective study were examined. Fecal pH and fecal short chain fatty acid (SCFA) concentrations were measured and tag-encoded FLX 16S rDNA amplicon pyrosequencing (bTEFAP) and quantitative real-time PCR were performed at baseline (10 d prior to the study) and after 2 weeks of treatment with a total treatment time of 6 weeks. Fecal scores for all dogs were assessed at baseline and every day for 6 wk after initiation of treatment. RESULTS: Alterations in the fecal microbiome were observed with a significant rise in Lactobacillaceae in the synbiotic group (P = 0.004) after 2 wk of treatment. A positive correlation was found between Lactobacillaceae and overall butyrate concentration (R = 0.62, p = 0.011) in all dogs. After 5 wk of treatment, there was an improved fecal score and fewer days of diarrhea (Χ2 = 5.482, P = 0.019) in the dogs given synbiotic, which coincided with a presumed contagious outbreak shared by all dogs in the study. CONCLUSIONS: Use of this synbiotic results in an increase in presumed beneficial bacterial flora of the host colon which was associated with a decrease in the prevalence of diarrhea in training sled dogs.

Soluble fiber dextrin and soluble corn fiber supplementation modify indices of health in cecum and colon of Sprague-Dawley rats.

The objective of this study was to evaluate health outcomes resulting from dietary supplementation of novel, low-digestible carbohydrates in the cecum and colon of Sprague-Dawley rats randomly assigned to one of four treatment groups for 21 days: 5% cellulose (Control), Pectin, soluble fiber dextrin (SFD), or soluble corn fiber (SCF). Rats fed Pectin had a higher average daily food intake, but no differences in final body weights or rates of weight gain among treatments were observed. No differences were observed in total short-chain fatty acid (SCFA) or branched-chain fatty acid (BCFA) concentrations in the cecum and colon of rats fed either SFD or SCF. The SFD and SCF treatments increased cecal propionate and decreased butyrate concentrations compared to Control or Pectin. Pectin resulted in increased BCFA in the cecum and colon. Supplementation of SFD and SCF had no effect on cecal microbial populations compared to Control. Consumption of SFD and SCF increased total and empty cecal weight but not colon weight. Gut histomorphology was positively affected by SFD and SCF. Increased crypt depth, goblet cell numbers, and acidic mucin were observed in both the cecum and colon of rats supplemented with SFD, SCF, and Pectin. These novel, low-digestible carbohydrates appear to be beneficial in modulating indices of hindgut morphology when supplemented in the diet of the rat.

Effects of dietary fiber on the feline gastrointestinal metagenome.

Four healthy adult cats were used in a crossover design to determine phylogeny and metabolic functional capacity of the cat's gastrointestinal microbiota using a metagenomic approach. Healthy adult cats (1.7 years old) were fed diets containing 4% cellulose, fructooligosaccharides (FOS), or pectin for 30 d, at which time fresh fecal samples were collected. Fecal DNA samples from each cat consuming each diet were subjected to 454 pyrosequencing. Dominant phyla determined using two independent databases (MG-RAST and IMG/M) included Firmicutes (mean=36.3 and 49.8%, respectively), Bacteroidetes (mean=36.1 and 24.1%, respectively), and Proteobacteria (mean=12.4 and 11.1%, respectively). Primary functional categories as determined by KEGG were associated with carbohydrates, clustering-based subsystems, protein metabolism, and amino acids and derivatives. Primary functional categories as determined by COG were associated with amino acid metabolism and transport, general function prediction only, and carbohydrate transport and metabolism. Analysis of carbohydrate-active enzymes revealed modifications in several glycoside hydrolases, glycosyl transferases, and carbohydrate-binding molecules with FOS and pectin consumption. While the cat is an obligate carnivore, its gut microbiome is similar regarding microbial phylogeny and gene content to omnivores.

Soluble fiber dextrins and pullulans vary in extent of hydrolytic digestion in vitro and in energy value and attenuate glycemic and insulinemic responses in dogs.

The objective of this research was to measure in vitro hydrolytic digestion characteristics, glycemic and insulinemic responses, and true metabolizable energy (TMEn) content of select soluble fiber dextrins (SFDs) and pullulans. The SFDs were derived either from tapioca starch or from corn starch. The pullulans were of low, intermediate, and high molecular weight. Soluble fiber dextrins varied in digestibility, with all substrates resulting in low to intermediate in vitro monosaccharide digestion. Pullulans were nearly completely hydrolyzed after simulated hydrolytic digestion. The glycemic response with dogs varied widely among SFDs, with all but one SFD substrate having lower glycemic response than maltodextrin (Malt). The pullulans all resulted in low glycemic values. Lower relative insulinemic responses (RIR) compared to the Malt control were noted for all SFDs and pullulans. True metabolizable energy (TMEn) values for SFDs obtained using roosters were lower than for Malt, with tapioca-based SFDs having numerically higher values than corn-based SFDs. Pullulans resulted in higher TMEn values than did SFDs. Soluble fiber dextrins and pullulans may be suitable candidates for reduced calorie and glycemic foodstuffs.

Carbohydrates blended with polydextrose lower gas production and short-chain fatty acid production in an in vitro system.

Maximizing health benefits of prebiotics, while limiting negative side effects, is of importance to the food industry. This study examined several oligosaccharides and their blends in an in vitro fermentation model. Substrates included medium- and long-chain fructooligosaccharides (FOS), oligofructose-enriched inulin, galactooligosaccharide, polydextrose (POL), and 50:50 substrate blends. Substrates and blends were fermented in vitro using human fecal inoculum, and fermentation characteristics were quantified at 0, 4, 8, and 12 hours. We hypothesized that mixtures of short- and long-chain oligosaccharides would generate less gas than do short-chain oligosaccharides and modulate gut microflora to a greater extent than do long-chain oligosaccharides. Carbohydrates blended with POL had decreased (P < .01) total gas volume and H(2) produced after 4, 8, and 12 hours of fermentation compared with individual carbohydrates. Mixing of 2 oligofructose-enriched inulin products led to less (P < .05) gas produced and a slower (P < .05) rate of production. When mixed with POL, all carbohydrates tested in the present study produced less total short-chain fatty acids (P < .04) and butyrate (P < .0001) after 12 hours of in vitro fermentation, compared with individual carbohydrates. The bifidogenic effect of medium-chain FOS and oligofructose-enriched inulin after 12 hours of in vitro fermentation was lower (P < .05) when mixed with POL. Mixing the pure carbohydrates with galactooligosaccharide increased (P < .05) bifidobacteria counts measured after 12 hours of in vitro fermentation, except when mixed with medium-chain FOS. In general, when mixed with POL, all carbohydrates had lower gas production, gas production rates, butyrate and total short-chain fatty acid production, and bifidobacteria counts than when fermented alone for 12 hours.