The term "dietary fibre" (DF) is, in most recent animal literature, used fo
r cell wall or storage non-starch polysaccharides (NSP) and lignin. The DF
can be measured as soluble, insoluble and total DF by enzymatic-gravimetric
methods or as soluble, insoluble and total NSP by enzymatic-chemical metho
ds and lignin by gravimetry. The NSP comprise 700-900 g kg(-1) of the plant
cell wall, with the remaining being lignin, protein, fatty acids, waxes, e
tc. plant cell wall NSP is a diverse group of molecules with varying degree
s of water solubility, size and structure, which may influence the theologi
cal properties of the gastrointestinal contents, flow of digesta and the di
gestion and absorption process to a variable degree. The action of NSP in t
he stomach and small intestine is essentially a physical one, in which the
plant cell either acts as barrier to the release of nutrients or increases
the viscosity of the liquid phase and restricts their absorption. However,
contradictory effects of DF are reported in the literature concerning their
effects on gastric emptying and rate of glucose absorption in small intest
ine presumably due to differences among studies in the form in which the DF
has been included (isolates or integrated part of cell wall structure). In
pigs, approximately 0.8 of fed NSP is recovered in digesta leaving the ile
um; the remaining being lost through microbial degradation in stomach and s
mall intestine. The NSP are degraded to a variable degree in the large inte
stine by anaerobic fermentation. The degradation of NSP in the large intest
ine depends on the degree of lignification, solubility and structure of the
polysaccharides. Analytical values concerning degree of lignification and
water solubility provide important information about the degradability of N
SP in the large intestine, while the effect of NSP on the digestion and abs
orption processes in the small intestine is more difficult to predict from
any of the chemical parameters currently measured. (C) 2001 Elsevier Scienc
e B.V. All rights reserved.