Effect dietary inulin on microbial ecosystem and concentrations of volatile fatty acids in rat's caecum.

摘要

The effect of inulin on feed intake, excreta output, microbial ecosystem and concentrations of volatile fatty acids in rats' caecum was investigated in 8-week-old male Wistar rats (n=21). The animals were divided randomly into three experimental groups of 7 rats each, which were kept in individual cages. Three experimental isoprotein and isoenergetic diets were prepared by providing different sources and amount of fermentable carbohydrate. The control diet contained 5% potato starch, while the IN-5 and the IN-10 diet contained 5 and 10% of inulin, respectively. Rats were fed with these diets and provided with distilled water ad libitum for 10 weeks. Dietary intake was monitored daily, while weight gain was recorded twice a week. Between days 30 and 41 of the experiment, a 10-day balance study was performed to determine the feed intake and excreta output. Transit time was determined with the help of chlorophiline (0.5% diet weight) as a colour marker. At the end of experiment, after a 12 h starvation, rats were sacrificed by thiopental injection and dissected to obtain samples of caecal digesta. Inclusion of 5 and 10% inulin in the rat's diet did not significantly affect feed intake, excreta output, its water content and transit time. However, in rats fed with high-inulin diet, a tendency to a higher water content of excreta and decrease of transit time was observed. Concentration of the volatile fatty acids in caecum, specially the butyrate, was significantly higher in rats fed with inulin supplemented diets without changing their mutual proportions. Inulin inclusion in the diet led to changes in caecal microflora populations, total counts of the coli form and decrease in anaerobic bacteria. When compared with the control group, the 10% inclusion of inulin lowered the total coli form and anaerobic bacteria.