Effect of guar gum on nitrogen secretion into isolated loops of jejunum in conscious growing pigs.

Four pigs, initially of 30 kg live weight, were surgically prepared with two re-entrant cannulas in the jejunum, 1.0 m apart. This allowed an isolated loop to be formed through which Ringer solutions were continuously perfused for 6.5-h periods per day. The effects of two Ringer solutions of contrasting composition on nitrogen secretion were measured in a preliminary study. The effects of guar gum (6.7 g/l) on N secretion during perfusions of solutions of glucose or of maltose (20 g/l) were measured. N secretion did not differ significantly between the two Ringer solutions. Addition of guar gum to the solution of glucose increased mean N secretion from 69.2 to 133.9 mg/m per 2 h; the corresponding values for the maltose solution were 75.5 and 120.2 mg/m per 2 h. In both cases the differences were significant (P less than 0.001). Differences between N secretion into glucose and maltose solutions were not significant, either without or with guar gum. Guar gum addition had a greater effect on N secretion in hours 5 and 6 than in hours 1 and 2 of perfusion. It was calculated that guar gum would have increased N section by the mucosa of the whole small intestine from approximately 15 to 27 g/d under the conditions of the study, assuming uniform secretion throughout the organ. These results suggest that certain types of dietary fibre may be important determinants of N secretion by the mucosa of the small intestine. They also suggest that changes in N secretion of this magnitude are of importance in N metabolism because the overall rate of protein synthesis in these pigs was probably about 100 g/d (expressed as N), using values from the literature.