Changes in intragastric meal distribution are better predictors of gastricemptying rate in conscious pigs than are meal viscosity or dietary fibre concentration

The effect of dietary fibre on the gastric emptying rate of solids is contr oversial. Similarly, the mechanisms by which it modulates food intake are p artially unknown. Gastric emptying and proximal v. distal stomach filling w ere evaluated in triplicate on four conscious pigs using scintigraphic imag ing. Each animal received in an isoenergetic manner a concentrate low-fibre diet enriched in starch (S) and two high-fibre diets based on sugar beet p ulp (BP) or wheat bran (WB). All meals had the same viscosity before ingest ion (100.0-100.5 Pa.s). Viscosity of the gastric contents was measured in f our additional animals fitted with a gastric cannula. The gastric emptying rate of BP diet was significantly slower than S and WB diets (t(1/2) 78.4 ( SEM 5.68), 62.8 (SEM 10.01) and 111.6 (SEM 10.82) min for S, WB and BP diet s respectively, P < 0.05). For BP diet only, rate of distal stomach filling was steady during the first 120 min after the meal whereas that of S and W B diets decreased in an exponential manner. Numerous backflow episodes from the distal into the proximal stomach were observed for BP diet that genera ted the larger intragastric viscosity (0.26 (SEM 0.03), 0.3 (SEM 0.02) and 0.52 (SEM 0.002) Pa.s for S, WB and BP respectively). In conclusion, viscos ity of the meal or the percentage total fibre, unlike viscosity of the gast ric contents, are poor predictors for emptying. The reduced emptying rate o bserved with BP is associated with major changes in intragastric distributi on of the meal absent with WB and S diets.