Studies on gastric digestion of protein and carbohydrate, gastric secretion and exocrine pancreatic secretion in the growing pig

Abstract

1. Six pigs, initially of 35 kg mean live weight, were each fitted with a re-entrant cannula. This was formed on either side of a short pouch of duodenum into which the pancreatic duct opened and which contained a simple cannula linked to the centre of the re-entrant cannula.2. Each pig received two diets: diet A was based on wheat starch, sucrose and casein, while diet B was based on barley and soya-bean meal. The diets were given in equal amounts at 12 h intervals.3. Digesta and pancreatic juice were collected continuously during three 12 h periods for each pig on each diet.4. Mean duodenal output: dietary intake values for diets A and B respectively were: digesta 1·80, 2·86; dry matter 1·05, 1·03; nitrogen 1·05, 1·06; trichloroacetic acid (TCA)-soluble N 7·69, 9·10; glucose 0·97, 0·89. For diet A the proportion of TCA-soluble N in total N rose from 13 to 50% during 12 h, while it was approximately 50% throughout 12 h for diet B.5. Mean total pepsin (EC3.4.23.1) activities (units/24 h) were 760449 (diet A) and 1466571 (diet B).6. Salivary and gastric secretions were calculated to be approximately 4 and 8 kg/24 h for diets A and B respectively.7. Mean flows in pancreatic juice (g/24 h) for diets A and B respectively were: juice 1204, 2182; protein 10·94, 12·10; N 1·98, 2·14; ash 9·46, 17·31; sodium 3·88, 6·91; potassium 0·23, 0·54: calcium 0·031, 0·046; phosphorus 0·024, 0·026.8. Mean total enzyme activities (units × 10−3/24 h) for diets A and B respectively were: trypsin (EC3.4.21.4) 138, 114; chymotrypsin (EC3.4.21.1) 84, 84; carboxypeptidase A (EC3.4.2.1) 5, 4; carboxypeptidase B (EC3.4.2.2) 15, 17; amylase (EC3.2.1.1) 1061, 981.9. It was calculated that the minimum amount of endogenous N from saliva and gastric secretion was 0·3–0·6 g in 24 h. This assumes no absorption of N occurred anterior to the duodenal cannula.