Servicio de Información Comunitario sobre Investigación y Desarrollo - CORDIS

Differential fermentation capabilities of gut microbiota along the intestinal tract

Initially, an in vitro experiment was conducted to examine differences in fermentability of four carbohydrate-rich feed ingredients, and two weaning piglet diets with and without these ingredients, using both the ileal contents and the faeces of unweaned piglets as inocula. In the first part of experiment, cumulative gas production was measured in time; using faecal inocula mixed from nine specially raised crossbred piglets (no creep feed or antibiotics) at three weeks of age. Inulin, lactulose, unmolassed sugar beet pulp, wheat starch and the two complete diets, were used as substrates, and fermented in vitro for 72 hrs.

Gas production was measured mainly as an indicator of the kinetics of fermentation. Fermentation end products including total gas, VFA, ammonia, and organic matter loss, were also measured. For those fermentations of individual ingredients, samples were also collected for PCR / DGGE analyses both before, and after the fermentation process, to study changes in the composition of the bacterial community.

This procedure was repeated one week later, using ileal contents from the same piglets as inoculum. There were of course, significant differences between the substrates, but also, and more importantly, between the inocula, both in terms of the overall fermentation characteristics, and the bacterial composition. The latter was an important finding, because it showed that, in vitro at least; the substrate used could lead to a significant shift in the bacterial population, both in terms of detectable composition, and the activity.

To determine whether this in vivo finding could also be detected in vivo an animal experiment was conducted to examine changes in fermentation end products in the gastrointestinal tract (GIT) of weaning piglets by the addition (or not) of fermentable carbohydrates in the diet. Specially raised piglets (neither antibiotics nor creep feeding) were weaned abruptly at four weeks of age. Piglets were randomly allotted to either a control diet (CON) or a diet enriched with fermentable carbohydrates (CHO; added inulin, lactulose, unmolassed sugar beet pulp, and wheat starch). Piglets were slaughtered on the 1st, 4th and 10th days after weaning.

Digesta samples were collected from different parts of the GIT (first half of small intestine, second half of small intestine, caecum, and colon) and analyzed for dry matter, volatile fatty acids (VFA) and ammonia. Feed intake, growth and feed conversion ratio were also recorded. Data analysis showed that there was no difference in production performances between the treatment groups.

Concentrations of VFA and ammonia were significantly different between diets, GIT sites of fermentation(P < 0.001), and the slaughtering day (P < 0.05). It was concluded that the addition of fermentable carbohydrates of varying fermentabilities (both in terms of rates and end-products) stimulated the production of fermentation end products in the four different areas of the GIT studied in weaning piglets. Quantitatively, the results were not the same as for in vitro differences, though this was not expected, and statistical correlations still need to be carried out. The qualitative agreement was very encouraging however.

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Zodiac, Marijkeweg 40
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