EFFECTS OF VARYING CONTENT OF SOLUBLE DIETARY FIBER FROM WHEAT-FLOUR AND OAT MILLING FRACTIONS ON GASTRIC-EMPTYING IN PIGS

Four pigs fitted with a gastric cannula were fed on a wheat-flour-base d diet (WF) and three oat-based diets, consisting mainly of oat flour (OF), rolled oats (RO) or oat bran (OB), for 1 week each, The stomach contents were collected quantitatively daily at 0.5, 1, 2, 3 or 5 h af ter feeding, The viscosity (mPa.s) of the liquid fraction of stomach c ontents 1 h after feeding was 1.7 with diet WF, 15 with diet OF, 30 wi th diet RO and approximately 400 with diet OB. The viscosity and the c oncentration of beta-glucan in the liquid phase was to some extent det ermined by the dietary level of beta-glucan in the diet, However, ther e was a trend towards a lower viscosity after longer exposure to the g astric juices, The correlation between logarithmic values for viscosit y and concentration of beta-glucan in the Liquid phase of digesta was r 0.45, On centrifugation of digesta there was a higher proportion pre sent in the sediment phase when the pigs were fed on diets with a high er content of soluble dietary fibre (DF), suggesting that the digesta was more coherent, This possibility was supported by the higher water- holding capacity (WHC) of the sediment, Feeding diets with oats contai ning a higher soluble DF content led to lower recoveries of digesta, P EG 4000 (Liquid-phase marker), and the DF components beta-glucan and a rabinoxylan in the first hour after feeding, No effect related to the DF content of the diet was seen in the gastric emptying of starch and Cr2O3 (solid-phase marker). In conclusion, soluble DF from oats increa sed the viscosity of stomach contents and increased the ability of the dry matter to retain water, Higher levels of soluble DF led to higher recoveries of digesta, the liquid phase and DF itself in the initial stage of gastric emptying, whereas no effect was seen on the gastric e mptying of starch.