In vitro influence of dietary protein and fructooligosaccharides on metabolism of canine fecal microbiota

BACKGROUND: The present in vitro study investigated whether the utilization of fructooligosaccharides (FOS) may influence canine fecal microbial population in presence of diets differing in their protein content and digestibility. Fresh fecal samples were collected from five adult dogs, pooled, and incubated for 24 h with the undigested residue of three diets: 1, Low protein high digestibility diet (LP HD, crude protein (CP) 229 g/kg); 2, High protein high digestibility diet (HP HD, CP 304 g/kg); 3, High protein low digestibility diet (HP LD, CP 303 g/kg) that had been previously subjected to enzymatic digestion. In the in vitro fermentation study, there were six treatments: 1) LP HD; 2) HP HD 3) HP LD; 4) LP HD + FOS; 5) HP HD + FOS; 6) HP LD + FOS. Fructooligosaccharides were added at the final concentration of 1.5 g/L. Samples of fermentation fluid were collected at 6 and 24 h of incubation. RESULTS: Values of pH were reduced by FOS at 6 and 24 h (P < 0.001); conversely, low protein digestibility and high dietary protein level resulted in higher pH at both sampling times (P < 0.001). At 24 h, FOS lowered ammonia (−10 %; P < 0.001) and resulted (P < 0.05) in higher concentrations of total volatile fatty acids (VFA) (+43 %), acetic acid (+14 %), propionic acid (+75 %) and n-butyric acid (+372 %). Conversely, at 24 h, low protein digestibility resulted (P < 0.01) in lower concentrations of acetic acid (−26 %), propionic acid (−37 %) and total VFA (−21 %). Putrescine concentrations were increased at 6 and 24 h of fermentation by low protein digestibility (+21 and 22 %, respectively; P < 0.05) and FOS (+18 and 24 %, respectively; P < 0.01). After 24 h of fermentation, high dietary protein level resulted in lower counts of lactobacilli and enterococci (−0.5 and −0.7 log cells/mL, respectively; P < 0.05) whereas low protein digestibility tended to increase counts of C. perfringens (+0.2 log cells/mL; P = 0.07). CONCLUSIONS: Results from the present study showed that diets rich in protein may exert negative influences on the canine intestinal ecosystem, slightly increasing the presence of ammonia and reducing counts of lactobacilli and enterococci. Moreover, the presence of poorly digestible protein resulted in lower concentrations of VFA. Conversely, administration of FOS may improve metabolism of canine intestinal microbiota, reducing ammonia concentrations and enhancing VFA production

Influence of the type of indigestible carbohydrate on plasma and urine short-chain fatty acid profiles in healthy human volunteers

&lt;p&gt;Background/Objectives: Health effects of whole grain foods are becoming more evident. In this study, we analysed the short-chain fatty acid profiles in urine and serum derived from the colonic fermentation process of &lt;sup&gt;13&lt;/sup&gt;C-barley meals, prepared from barley grown under &lt;sup&gt;13&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt; atmosphere.&lt;/p&gt; &lt;p&gt;Subjects/Methods: In a crossover study, five volunteers ingested intact barley kernels (high content of non-starch polysaccharides (NSP) and resistant starch (RS)) and barley porridge (high content of NSP only). Using a newly developed stable isotope technology, we monitored 14 and 24 h postprandially 13C-acetate, 13C-propionate and 13C-butyrate in plasma and urine, respectively. The oro-cecal transit time (OCTT) of the meals was measured with the hydrogen breath test.&lt;/p&gt; &lt;p&gt;Results: The OCTT was 6 h and did not differ between the two test meals. An increase of 13C-acetate was observed already early after ingestion of the meals (&#8736;6 h) and was attributed to early fermentation of the test meal. A rise in plasma 13C-propionate in the fermentation phase could only be detected after the porridge and not after the kernel meal. An increase in 13C-butyrate was only found in the fermentation phase and was higher after the barley kernels. Urine 13C-short-chain fatty acids data were consistent with these observations.&lt;/p&gt; &lt;p&gt;Conclusions: The difference in the profiles of 13C-acetate, 13C-propionate and 13C-butyrate indicates that NSP combined with RS results in an altered fermentation profile than dietary fibre alone.&lt;/p&gt