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.

Pediatric obesity and nonalcoholic steatohepatitis (NASH) are on the rise in industrialized countries, yet our ability to mechanistically examine this relationship is limited by the lack of a suitable higher animal models. Here, we examined the effects of high-fat, high-fructose corn syrup, high-cholesterol Western-style diet (WD)-induced obesity on NASH and cecal microbiota dysbiosis in juvenile Ossabaw swine. Juvenile female Ossabaw swine (5 wk old) were fed WD (43.0% fat; 17.8% high-fructose corn syrup; 2% cholesterol) or low-fat diet (CON/lean; 10.5% fat) for 16 wk ( n = 6 each) or 36 wk ( n = 4 each). WD-fed pigs developed obesity, dyslipidemia, and systemic insulin resistance compared with CON pigs. In addition, obese WD-fed pigs developed severe NASH, with hepatic steatosis, hepatocyte ballooning, inflammatory cell infiltration, and fibrosis after 16 wk, with further exacerbation of histological inflammation and fibrosis after 36 wk of WD feeding. WD feeding also resulted in robust cecal microbiota changes including increased relative abundances of families and genera in Proteobacteria ( P < 0.05) (i.e., Enterobacteriaceae, Succinivibrionaceae, and Succinivibrio) and LPS-containing Desulfovibrionaceae and Desulfovibrio and a greater ( P < 0.05) predicted microbial metabolic function for LPS biosynthesis, LPS biosynthesis proteins, and peptidoglycan synthesis compared with CON-fed pigs. Overall, juvenile Ossabaw swine fed a high-fat, high-fructose, high-cholesterol diet develop obesity and severe microbiota dysbiosis with a proinflammatory signature and a NASH phenotype directly relevant to the pediatric/adolescent and young adult population.

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.

Soy protein is effective at preventing hepatic steatosis; however, the mechanisms are poorly understood. We tested the hypothesis that soy versus dairy protein-based diet would alter microbiota and attenuate hepatic steatosis in hyperphagic Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Male OLETF rats were randomized to “Western” diets containing milk protein isolate (MPI), soy protein isolate (SPI), or 50:50 MPI/SPI (MS) (n=9–10/group; 21% kcal protein) for 16 weeks. SPI attenuated (P<0.05) fat mass and percent fat by ~10% compared with MS, but not compared with MPI. Serum TBAR and total and LDL-cholesterol concentrations were lower (P<0.05) with dietary SPI versus MPI and MS. Histological hepatic steatosis was lower (P<0.05) in SPI compared with MPI or MS. Lipidomic analyses revealed reductions (P<0.05) in hepatic diacylglycerols but not triacylglycerols in SPI compared with MPI, which was associated with lower hepatic de novo lipogenesis (ACC, FAS, and SCD-1 protein content, and hepatic 16:1 n-7 and 18:1 n-7 PUFA concentrations) (P<0.05) compared with MPI and MS; however, MPI displayed elevated hepatic mitochondrial function compared with SPI and MS. Fecal bacterial 16S rRNA analysis revealed SPI-intake elicited increases (P<0.05) in Lactobacillus and decreases (P<0.05) in Blautia and Lachnospiraceae suggesting decreases in fecal secondary bile acids in SPI rats. SPI and MS exhibited greater (P<0.05) hepatic Fxr, Fgfr4, Hnf4a, HmgCoA reductase and synthase mRNA expression compared with MPI. Overall, dietary SPI compared with MPI decreased hepatic steatosis and diacylglycerols, changed microbiota populations, and altered bile acid signaling and cholesterol homeostasis in a rodent model of obesity.

Panasevich MR, Morris EM, Chintapalli SV, Wankhade UD, Shankar K, Britton SL, Koch LG, Thyfault JP, Rector RS. Gut microbiota are linked to increased susceptibility to hepatic steatosis in low-aerobic-capacity rats fed an acute high-fat diet. Am J Physiol Gastrointest Liver Physiol 311: G166 -G179, 2016. First published June 10, 2016; doi:10.1152/ajpgi.00065.2016.-Poor aerobic fitness is linked to nonalcoholic fatty liver disease and increased all-cause mortality. We previously found that rats with a low capacity for running (LCR) that were fed an acute high-fat diet (HFD; 45% kcal from fat) for 3 days resulted in positive energy balance and increased hepatic steatosis compared with rats that were highly aerobically fit with a high capacity for running (HCR). Here, we tested the hypothesis that poor physiological outcomes in LCR rats following acute HFD feeding are associated with alterations in cecal microbiota. LCR rats exhibited greater body weight, feeding efficiency, 3 days of body weight change, and liver triglycerides after acute HFD feeding compared with HCR rats. Furthermore, compared with HCR rats, LCR rats exhibited reduced expression of intestinal tight junction proteins. Cecal bacterial 16S rDNA revealed that LCR rats had reduced cecal Proteobacteria compared with HCR rats. Microbiota of HCR rats consisted of greater relative abundance of Desulfovibrionaceae and unassigned genera within this family, suggesting increased reduction of endogenous mucins and proteins. Although feeding rats an acute HFD led to reduced Firmicutes in both strains, short-chain fatty acid-producing Phascolarctobacterium was reduced in LCR rats. In addition, Ruminococcae and Ruminococcus were negatively correlated with energy intake in the LCR/HFD rats. Predicted metagenomic function suggested that LCR rats had a greater capacity to metabolize carbohydrate and energy compared with HCR rats. Overall, these data suggest that the populations and metabolic capacity of the microbiota in low-aerobically fit LCR rats may contribute to their susceptibility to acute HFD-induced hepatic steatosis and poor physiologic outcomes. microbiota; short-chain fatty acids; aerobic fitness; NAFLD A SEDENTARY LIFESTYLE AND low aerobic fitness are strong independent risk factors for cardiovascular disease and allcause mortality (28). Nonalcoholic fatty liver disease (NAFLD) is becoming more prevalent and is increasing concomitant with the rise in obesity (51). Progression of the disease begins with simple hepatic steatosis, which in some individuals, may progress to more severe liver diseases (i.e., inflammation, fibrosis, and cirrhosis). Several studies have shown that low aerobic fitness and physical inactivity are inversely related to the development and progression of NA-FLD (10, 42, 44); however, the mechanisms explaining this link are poorly understood. We previously demonstrated that sedentary rats selectively bred for low-capacity running (LCR) fed an acute high-fat diet (HFD; 45% kcal from fat) for 3 days were more susceptible to developme...

The objective of the present study was to utilise an accurate canine pedometer methodology and to assess the relationship between activity and body condition score (BCS) in dogs. Initial methodology validation used videography and pedometer step measurements to assess actual steps taken in comparison with pedometer readings for twenty large, medium and small dogs. During the validation, dogs considered to be medium or large breed showed no significant difference between pedometer readings and actual steps taken. A total of seventy-seven obese and non-obese dogs over 35 cm (14 inches) shoulder height and over 10 kg were recruited from a dog obesity clinic and a community sample to assess daily walking activity. Body condition scoring and pedometer steps were assessed on three separate weeks during a 10-week period. During the activity monitoring, daily step counts ranged from 5555 to 39 970 steps/d among the seventy-seven medium and large dogs. Dogs' BCS were inversely correlated with average daily steps (Spearman's r ¼ 20·442, P ,0·0001). The present study identified a significant inverse correlation between daily walking steps and BCS over a range from 4 to 9 out of 9 (P, 0·0001).

The gut microbiome plays a critical role in the onset and progression of obesity and the metabolic syndrome. However, it is not well documented whether the cecal vs. the fecal microbiome is more relevant when assessing their contributions to these diseases. Here, we amplified the V4 region of the 16S rRNA gene from cecal and fecal samples of female Ossabaw swine fed a low-fat control diet (10.5% fat, n = 4) or Western diet (43.0% fat, 17.8% high fructose corn syrup, 2% cholesterol; n = 3) for 36 wk. Obesity significantly lowered alpha-diversity ( P < 0.05), and there was clear separation in beta-diversity between lean and obese pigs, as well as between cecal and fecal samples ( P < 0.05). Obesity dramatically increased ( P < 0.05) the Firmicutes:Bacteroidetes ratio in fecal samples, and Actinobacteria was higher ( P < 0.05) in fecal vs. cecal samples in obese pigs. Cyanobacteria, Proteobacteria, and Fusobacteria were increased ( P < 0.05), while Spirochaetes, Tenericutes, and Verrucomicrobia were decreased ( P < 0.05) in obese vs. lean pigs. Prevotellaceae was reduced ( P < 0.05) in obese fecal vs. cecal samples. Moreover, cecal samples in obese had greater ( P < 0.05) predicted metabolic capacity for glycan biosynthesis and metabolism and LPS biosynthesis compared with fecal. Obese pigs also had greater ( P < 0.05) capacity for carbohydrate metabolism, which was driven by obese fecal rather than cecal samples and was opposite in lean pigs ( P < 0.05). The observed differences in pro-inflammatory microbiota and their metabolic capacity in cecal vs. fecal samples of obese pigs provide new insight into evaluating the microbiome in the pathogenesis of obesity and metabolic disease.

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.