Exogenous and endogenous contribution to nitrogen fluxes in the digestive tract of pigs fed a casein diet. I. Contributions of nitrogen from the exocrine pancreatic secretion and the bile

The aim of the present work was to study the endogenous contribution of the exocrine pancreatic and biliary secretions to the total endogenous nitrogen production in the pig. Three growing Large White pigs weighing 45 +/- 2.5 kg were fitted with permanent fistulae in the pancreatic duct, the bile duct and the duodenum. They were adapted to a semi-synthetic casein diet for 14 d before surgery. In a 7-d post-operative period and an 8-d experimental period, they were fed the same diet. Secretion rates were recorded, total nitrogen and TCA (trichloroacetic acid) insoluble nitrogen were determined in representative pancreatic juice and bile samples. Daily pancreatic juice and bile flow rates were very similar: 1,850 and 1,820 ml, respectively. The amount of endogenous total nitrogen secreted in the intestinal lumen was 3.6 g per day: 1.9 g N through pancreatic secretion and 1.7 g N through bile secretion. Pancreatic nitrogen increased after meal intake, whilst the kinetics of nitrogen production in the bile were not affected. Throughout the experiment, the mean percentage of TCA insoluble nitrogen was 78.1% in pancreatic juice and 72.3% in bile.