The relative contribution of novel fibers such as polydextrose and soluble corn fiber (SCF) to the human gut microbiome and its association with host physiology has not been well studied. This study was conducted to test the impact of polydextrose and SCF on the composition of the human gut microbiota using 454 pyrosequencing and to identify associations among fecal microbiota and fermentative end-products. Healthy adult men (n = 20) with a mean dietary fiber (DF) intake of 14 g/d were enrolled in a randomized, double-blind, placebo-controlled crossover study. Participants consumed 3 treatment snack bars/d during each 21-d period that contained no supplemental fiber (NFC), polydextrose (PDX; 21 g/d), or SCF (21 g/d) for 21 d. There were no washout periods. Fecal samples were collected on d 16-21 of each period; DNA was extracted, followed by amplification of the V4-V6 region of the 16S rRNA gene using barcoded primers. PDX and SCF significantly affected the relative abundance of bacteria at the class, genus, and species level. The consumption of PDX and SCF led to greater fecal Clostridiaceae and Veillonellaceae and lower Eubacteriaceae compared with a NFC. The abundance of Faecalibacterium, Phascolarctobacterium, and Dialister was greater (P < 0.05) in response to PDX and SCF intake, whereas Lactobacillus was greater (P < 0.05) only after SCF intake. Faecalibacterium prausnitzii, well known for its antiinflammatory properties, was greater (P < 0.05) after fiber consumption. Principal component analysis clearly indicated a distinct clustering of individuals consuming supplemental fibers. Our data demonstrate a beneficial shift in the gut microbiome of adults consuming PDX and SCF, with potential application as prebiotics.

The objective of the present study was to evaluate digestive physiological outcomes elicited by functional fibres fed to healthy adult men. A total of twenty-one healthy adult men were utilised in a cross-over design. Each subject received polydextrose (PDX) or soluble maize fibre (SCF) (21 g/d) or no supplemental fibre (no fibre control; NFC) in a snack bar. Periods were 21 d and faeces were collected during the last 5 d of each period. Food intake, including fibre intake, did not differ among treatments. Flatulence (P¼ 0·001) and distention (P¼ 0·07) were greatest when subjects consumed PDX or SCF. Reflux was greater (P¼ 0·04) when subjects consumed SCF compared with NFC. All tolerance scores were low (, 2·5), indicating only slight discomfort. Faecal ammonia, 4-methylphenol, indole and branchedchain fatty acid concentrations were decreased (P,0·01) when subjects consumed the functional fibre sources compared with NFC. Faecal acetate, propionate and butyrate concentrations were lower (P, 0·05) when subjects consumed PDX compared with SCF and NFC. Faecal pH was lower (P¼0·01) when subjects consumed SCF compared with NFC, while PDX was intermediate. Faecal wet weight was greatest (P¼ 0·03) when subjects consumed SCF compared with NFC. Faecal dry weight tended to be greater (P¼0·07) when subjects consumed PDX compared with NFC. The functional fibres led to 1·4 and 0·9 g (PDX and SCF, respectively) increases in faecal dry mass per g supplemental fibre intake. Bifidobacterium spp. concentrations were greater (P,0·05) when subjects consumed SCF compared with NFC. These functional fibres appear to be beneficial to gut health while leading to minimal gastrointestinal upset.

Nontargeted metabolomics analyses were used (1) to compare fecal metabolite profiles of healthy breast-fed (BF) and formula-fed (FF) infants before and during in vitro fermentation in batch culture and (2) to evaluate fecal metabolomics in assessing infant diet. Samples from healthy BF (n = 4) or FF (n = 4) infants were individually incubated at 37( °)C in anaerobic media containing 1% (wt/vol) galactooligosaccharides, 6'-sialyllactose, 2'-fucosyllactose, lacto-N-neotetraose, inulin, and gum arabic for up to 6 h, and supernatants were analyzed using GC/MS and LC/MS/MS to assess changes in various compounds. Comparison of over 250 metabolites prior to incubation showed that BF samples contained higher relative concentrations (P ≤ 0.05) of 14 compounds including human milk oligosaccharides and other metabolites presumably transferred through breast feeding (linoelaidate, myo-inositol) (P ≤ 0.05). Conversely, feces from FF infants contained 41 identified metabolites at higher levels (P ≤ 0.05) with many indicative of carbon limitation and protein fermentation. Our data are consistent with the notion that carbon-limited cultures catabolize protein and amino acids to obtain energy, whereas the provision of fermentable carbohydrate creates anabolic conditions relying on amino acids for bacterial growth. Results also suggest that fecal metabolomics can be a useful tool for studying interactions among diet, microbes, and host.

Insects can serve as a novel high-quality protein source for pet foods. However, there is an absence of research investigating the use of insects in pet food. The study objective was to evaluate the apparent total tract digestibility and possible health effects of diets containing graded levels of cricket (Gryllodes sigillatus) meal fed to healthy adult dogs. Thirty-two adult Beagles were randomly assigned to one of four dietary treatments: 0%, 8%, 16%, or 24% cricket meal. Dogs were fed their respective diet for a total of 29 d with a 6-d collection phase. Fecal samples were collected daily during the collection phase to measure total fecal output as well as apparent total tract digestibility for dry matter (DM), organic matter, crude protein, fat, total dietary fiber, and gross energy. Blood samples were taken prior to the study and on day 29 for hematology and chemistry profiles. Data were analyzed in a mixed model including the fixed effects of diet and sex. Total fecal output increased on both an as-is (P = 0.030) and DM basis (P = 0.024). The apparent total tract digestibility of each nutrient decreased (P &lt; 0.001) with the increasing level of cricket meal inclusion. All blood values remained within desired reference intervals indicating healthy dogs. Slight fluctuations in blood urea nitrogen (P = 0.037) and hemoglobin (P = 0.044) levels were observed but were not considered of biological significance. Even with the decrease in digestibility with the inclusion of cricket meal, diets remained highly digestible at greater than 80% total apparent digestibility. In conclusion, crickets were demonstrated to be an acceptable ingredient for dog diets.

This study sought to determine the fermentation potential of human milk oligosaccharides by mixed cultures of fecal microbiota from breast-fed (BF; n = 4) and formula-fed (FF; n = 4) infants. Infant fecal inocula were incubated with galactooligosaccharide (GOS), gum arabic (GA), HP inulin (HP), 2'-fucosyllactose (2'FL), 6'-sialyllactose (6'SL), and lacto-N-neotetraose (LNnt). GOS, 2'FL, and LNnT had a lower pH than other substrates after 3 h (P < 0.05). Total short chain fatty acids were greater in FF compared to BF infants at 6 h (P = 0.03) and 12 h (P = 0.01). GOS, 2'FL, and LNnT led to more lactate than 6'SL, HP, and GA (P < 0.05). Bifidobacteria populations were greater (P = 0.02) in FF at 6 and 12 h. Overall, GOS, 2'FL, and LNnT were rapidly fermented by infant fecal inocula, 6'SL and HP had intermediate fermentability, while GA had little fermentation. Inocula from FF infants fermented substrates more rapidly than inocula from BF infants, which should be accounted for when evaluating substrate fermentability. These data will aid in future infant formulas to promote optimal gut health in FF infants.

Potato fiber (PF), a coproduct of potato starch manufacture, was evaluated as a potential novel fiber source in dog food. Potato fiber contained 55% total dietary fiber, 29% starch, 4% crude protein, and 2% acid-hydrolyzed fat. The PF substrate was evaluated for chemical composition, in vitro digestion and fermentation characteristics, and in vivo responses. For the in vitro hydrolytic-enzymatic digestion and fermentation experiment, raw and cooked PF substrates were first subjected to hydrolytic-enzymatic digestion to determine OM disappearance and then fermented using dog fecal inoculum. Fermentation characteristics were then measured at 0, 3, 6, 9, and 12 h. For the in vivo experiment, 10 female mixed-breed dogs (6.13±0.17 yr; 22±2.1 kg) were provided 5 diets with graded concentrations (0%, 1.5%, 3%, 4.5%, or 6%) of PF in a replicated 5×5 Latin square design. Dogs were acclimated to the test diet for 10 d, followed by 4 d of total fecal collection. Fresh fecal samples were collected to measure fecal pH and fermentation end products. In vitro digestion revealed that raw and cooked PF were 32.3% and 27.9% digested enzymatically, whereas in vitro fermentation showed that PF was fermentable through 9 h. Raw PF had greater (P<0.05) acetate, propionate, and total short-chain fatty acid (SCFA) concentrations at the 12-h time point compared with cooked PF. The in vivo experiment showed no differences in apparent total tract DM, OM, CP, acid-hydrolyzed fat, or energy digestibility of diets containing graded concentrations of PF. However, total dietary fiber digestibility exhibited a linear increase (P<0.01) with increasing PF concentrations in the diet. Overall, linear increases (P<0.01) were observed for all individual and total SCFA, with a concomitant linear decrease (P<0.01) in fecal pH with increasing dietary PF. Fecal protein catabolite concentrations were low or undetectable, with the exception of spermidine, which exhibited a linear increase with increasing concentrations of PF. These findings indicated that inclusion of PF elicited favorable fermentation characteristics without negatively affecting nutrient digestibility or stool characteristics, indicating that PF could be a functional dietary fiber source in dog foods.

Pet foods may be formulated with decreased starch to meet consumer demands for less processed diets. Fats and oils may be added to low-starch diets to meet energy requirements, but little is known about its effects on canine health. The study objective was to evaluate the effects of feeding healthy adult dogs low carbohydrate, high-fat diets on apparent total tract digestibility, fecal characteristics, and overall health status. Eight adult Beagles were enrolled in a replicated 4 × 4 Latin Square design feeding trial. Dogs were randomly assigned to one of four dietary fat level treatments (T) within each period: 32% (T1), 37% (T2), 42% (T3), and 47% (T4) fat on a dry matter basis. Fat levels were adjusted with the inclusion of canola oil added to a commercial diet. Each dog was fed to exceed its energy requirement based on NRC (2006). Blood samples were analyzed for complete blood counts, chemistry profiles, and canine pancreatic lipase immunoreactivity levels. Apparent total tract digestibility improved (P &lt; 0.05) as the fat level increased for dry matter, organic matter, fat, and gross energy. Fecal output decreased as levels of fat increased in the diet (P = 0.002). There was no effect of fat level on stool quality or short-chain fatty acid and ammonia concentrations in fecal samples (P ≥ 0.20). Blood urea nitrogen levels decreased with increased fat level (P = 0.035). No significant differences were seen in canine pancreatic lipase immunoreactivity (P = 0.110). All blood parameters remained within normal reference intervals. In summary, increased dietary fat improved apparent total tract digestibility, did not alter fecal characteristics, and maintained the health status of all dogs.

Dietary fermentable fiber is known to benefit intestinal health of companion animals. Soluble corn fiber (SCF) was evaluated for its chemical composition, nitrogen-corrected true ME (TMEn) content, in vitro digestion and fermentation characteristics, and in vivo effects on nutrient digestibility, fecal fermentation end products, and modulation of the fecal microbiome of dogs. Soluble corn fiber contained 78% total dietary fiber, all present as soluble dietary fiber; 56% was low molecular weight soluble fiber (did not precipitate in 95% ethanol). The SCF also contained 26% starch and 8% resistant starch and had a TMEn value of 2.6 kcal/g. Soluble corn fiber was first subjected to in vitro hydrolytic-enzymatic digestion to determine extent of digestibility and then fermented using dog fecal inoculum, with fermentative outcomes measured at 0, 3, 6, 9, and 12 h. Hydrolytic-enzymatic digestion of SCF was only 7%. In vitro fermentation showed increased (P < 0.05) concentrations of short-chain fatty acids through 12 h, with acetate, propionate, and butyrate reaching peak concentrations of 1,803, 926, and 112 μmol/g DM, respectively. Fermentability of SCF was higher (P < 0.05) than for cellulose but lower (P < 0.05) than for pectin. In the in vivo experiment, 10 female dogs (6.4 ± 0.2 yr and 22 ± 2.1 kg) received 5 diets with graded concentrations of SCF (0, 0.5, 0.75, 1.0, or 1.25% [as-is basis]) replacing cellulose in a replicated 5 × 5 Latin square design. Dogs were first acclimated to the experimental diets for 10 d followed by 4 d of total fecal collection. Fresh fecal samples were collected to measure fecal pH and fermentation end products and permit a microbiome analysis. For microbiome analysis, extraction of DNA was followed by amplification of the V4 to V6 variable region of the 16S rRNA gene using barcoded primers. Sequences were classified into taxonomic levels using a nucleotide basic local alignment search tool (BLASTn) against a curated GreenGenes database. Few changes in nutrient digestibility or fecal fermentation end products or stool consistency were observed, and no appreciable modulation of the fecal microbiome occurred. In conclusion, SCF was fermentable in vitro, but higher dietary concentrations may be necessary to elicit potential in vivo responses.