Degradation and physicochemical changes of barley and pea fibre along the gastrointestinal tract of pigs

The degradation of barley and pea fibres along the gastrointestinal tract (GIT) of pigs and its relation to changes in some of their physicochemical properties were investigated. Ileal and caecal digesta containing pea cotyledon fibre showed the highest (P<0.05) swelling (33.1-36.7 ml g(-1) DM) and water retention capacity measured by centrifugation (17.9-21.2 g g(-1) DM) and by osmotic pressure (9.0-9.1 g g(-1) DM). The particle size of barley hull did not change along the GIT (160-207 mu m), whereas that of pea cotyledon and pea hull was drastically reduced in faeces (62-65 mu m) compared with the ileum and caecum (198-415 mu m). The digestibility of non-starch polysaccharides (NSP) was lowest for barley hull in the ileum (5% of intake), caecum (0% of intake) and faeces (26% of intake). The digestibility of NSP was highest for pea cotyledon fibre and dehulled barley in the proximal hindgut and for pea cotyledon fibre in faeces (96% of intake for pea cotyledon vs 74-82% of intake for dehulled barley and pea hull). In conclusion, hydration properties and particle size add valuable information when describing the fermentation of fibres in the GIT. However, they cannot be used alone as indicators of the extent of fermentation of different fibres. The results also suggested that the fibre source and the organisation and lignification of the cell walls lead to different fermentation processes along the GIT of pigs. (C) 2001 Society of Chemical Industry.