The effects of feeding and withholding food on the canine small intestinal microbiota.

Prolonged lack of enteral feeding has a negative impact on gut physiology, potentially via microbiota modulation. The aims were to investigate the impact of fasting and post-prandial changes in canine jejunal microbiota. To study post-prandial effects, jejunal brushings were analyzed in 8 healthy fistulated dogs 15 min before feeding (baseline) and hourly for 8 h after feeding. To study effects of withholding food (WF), daily samples were collected for 15 days from 5 dogs. The first 5 days (PRE) dogs were fed regular diet. Food was withheld the next 5 days (days 6-10). For days 11-15 (POST), the original diet was reintroduced. Microbiota was characterized via denaturing gradient gel electrophoresis and 454-pyrosequencing of 16S rRNA genes. In the post-prandial study, no changes in microbiome structure were seen after feeding (ANOSIM, P = 0.28), but Betaproteobacteria (P = 0.04) and Bacteroidales decreased compared to baseline. Species richness decreased by 300 min (P = 0.04). During WF, microbiota structure differed from PRE and POST period (P = 0.001). During WF, species richness did not vary over time (P = 0.69). In conclusion, a prolonged period of food withholding results in altered jejunal microbiota. How these changes affect the microbiota metabolism warrants further studies.