ABSTRACT: The impact of dietary fiber on fecal digestion
is well-known and provides a comprehensive
approach toward nutrient digestibility and availability.
Little quantitative information is available on digestion
of fiber in the different segments of the gastrointestinal
tract (GIT). The objectives of this study were to obtain
a method allowing the quantification of the digestive
process in different segments of the GIT and to study
the impact of dietary fiber on nutrient digestibility. Six
barrows (average initial BW of 30 kg and fitted with a
simple T-cannula at the proximal duodenum and caudal
ileum) were used in a replicated 3 × 3 Latin square
design. In each period, pigs were offered 1 of 3 diets
differing in fiber content (low, medium, and high). Differences
in fiber content were created by replacing
wheat and barley with wheat bran. Titanium dioxide
was included in the diet as an indigestible marker todetermine the apparent digestibility coefficients in different
segments of the GIT. The apparent digestibility
of ash, CP, DM, and OM increased in the different
segments of the GIT. Duodenal digestibility coefficients
were negative for ash (e.g., −39.9% for the mediumand
high-fiber diets), indicating important endogenous
mineral secretions by the stomach and digestive glands.
The duodenal digestibility of other nutrients and OM
were positive but close to zero and numerically lower
in the diets with the greater fiber contents. The fiber
content in the diet did not affect the apparent ileal
digestibility of nutrients. Increasing the fiber content
in the diet affected the fecal digestibility of CP, ether
extract, and energy (P < 0.01). The method used for
studying sites of digestion in the digestive tract provides
promising results, but it is limited due to the high
variability that is likely caused by sampling limitations
and variation between animals.