Breakdown of plant carbohydrates in the digestive tract of pigs fed on wheat- or oat-based rolls

Cell wall materials from various cellular tissues of cereals may potentiall y influence the digestion and absorption processes in different ways. The o bjective of the present investigation was to study the breakdown of plant c arbohydrates in the gastrointestinal tract of pigs fed a low-fibre (LF; 65g kg(-1) dry matter) wheat flour-based diet and two high-fibre diets with ad ded insoluble fibre from wheat bran (HFWB; 112g kg(-1) dry matter) or solub le fibre from oat bran (HFOB; 108g kg(-1) dry matter). The diets were formu lated to provide similar to 0.31 energy from fat, similar to 0.18 energy fr om protein and similar to 0.51 energy from carbohydrates and were offered a s baked rolls to eight ileum-cannulated hypercholesterolemic pigs in a cros sover design. Carbohydrates were the predominant heal constituent, with mos t of the carbohydrates present as non-starch polysaccharides (NSP). Starch in all diets was almost completely digested at this site of the gastrointes tinal tract, with digestibility values above 0.99. The ingested amount of N SP was quantitatively recovered in ileal materials with the wheat-based die ts, while there was a significant loss of 0.27 of NSP primarily as mixed li nked (1-->3) (1-->4)-beta-D-glucan with diet HFOB. The concentration and fl ow of lactic acid were also highest in the ileum after feeding diet HFOB, i ndicating that beta-glucan stimulated lactic acid formation. Any soluble co mponents that reached the large intestine were almost completely broken dow n, while the digestibility of insoluble NSP constituents was significantly lower for diets LF and HFWB than for diet HFOB, The high degradation of oat bran resulted in a lower effect on faecal dry and wet bulking than was fou nd with wheat bran. In conclusion, cereal starch was practically completely degraded in the small intestine, while the site and extent of NSP degradat ion, lactic acid formation and bullring properties were influenced by the f ibre source. (C) 2000 Society of Chemical Industry.