The effect of age and weaning on the activities of digestive enzymes with emphasis on the lipolytic enzymes before and after weaning was investigated. The activities of amylase, chymotrypsin, trypsin, carboxyl ester hydrolase, pancreatic lipase, and colipase in pancreatic tissue and the activity of gastric lipase in the cardiac mucosa of the stomach in 45 pigs were response variables. The activity of trypsin was not affected by weaning and the rate of increase was similar during the whole experiment. The activities of chymotrypsin and amylase decreased at weaning (P < .05). After weaning the activity of chymotrypsin increased more slowly than before weaning (P < .001), whereas the rate of increase of amylase activity remained unchanged. Lipase, colipase, and carboxyl ester hydrolase activities decreased at weaning (P < .001), whereas gastric lipase activity increased at weaning (P < .01). The development of lipase, colipase, and carboxyl ester hydrolase activity decreased postweaning (P < .01), whereas gastric lipase activity increased before weaning and remained constant after weaning. Pancreatic lipase had a considerably higher capacity for hydrolyzing tributyrin, and the total activity of pancreatic lipase was up to 600 times higher than that of gastric lipase. The lipolytic enzymes displayed a non-parallel pattern of development, and we suggest that this reflects the importance of these enzymes during the suckling and postweaning phases, respectively. However, the significance of gastric lipase for the digestion of fat in pigs remains to be elucidated.

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The effect of lactic acid supplementation to the starter diet, on pancreatic secretion in pigs after weaning was studied in three crossbred piglets (Duroc, Danish Landrace and Yorkshire). The pigs were weaned at 28 days of age, and adapted to live in metabolic cages for one week, after which the piglets were surgically fitted with a pancreatic duct catheter and a duodenal T-cannula for chronic collection of the pancreatic juice. Studies were then carried out over a period of three weeks, during which the piglets were fed three times a day (at 08.00, 15.00, and 22.00 h). During period I , the piglets were fed with a standard weaner diet (control), during period II with a standard weaner diet supplemented with 2.5 % lactic acid period (lactic acid) and during period III with a standard wea ner diet (control). Beginning four days after surgery, samples of pancreatic juice were taken hourly from 08.00 to 16.00 h. During period II , when lactic acid was added to the feed, the mean for all measured parameters of pancreatic secretion, except bicarbonate, increased in comparison to their values during period I . However this increase was only significant for volume and protein content. In contrast, during period III , when lactic acid was removed, there were no statistically significant changes in any of the measured parameters of pancreatic secretion compared to their values in period II. Our data strongly indicate that dietary supplementation with lactic acid stimulates pancre atic secretion in piglets after weaning.