KINETICS OF PANCREATIC-JUICE SECRETION IN RELATION TO DUODENAL MIGRATING MYOELECTRIC COMPLEX IN PRERUMINANT AND RUMINANT CALVES FED TWICE-DAILY

Daily secretion of pancreatic juice, including postprandial responses to food, was investigated in two groups of calves: preruminant (fed wi th liquid food) and ruminant (fed with solid food). Male Friesian calv es (1 week old and 6 weeks old) were surgically fitted with a pancreat ic duct catheter, duodenal cannula and two duodenal electrodes. Contin uous 24 h collections of pancreatic juice and myoelectrical recordings were performed with minimal restraint and disturbance of animals. In both groups of calves clear periodic fluctuations in pancreatic juice secretion (volume, protein output and trypsin activity) coinciding wit h duodenal migrating myoelectric complexes (MMC) were recorded. Secret ion of juice per cycle and per day was greater in ruminant calves, but the frequency and amplitude of cycles were lower in this group. There were no differences between day and night-time preprandial pancreatic cycles and duodenal MMC in preruminant calves, whilst in ruminant cal ves, evening MMC were longer than morning MMC. The pancreatic cephalic phase (increase of volume flow, protein output and trypsin activity d uring and just after food intake) was significant only in preruminant calves following morning feeding. Postprandial pancreatic cycles did n ot differ from preprandial cycles, except the pancreatic cycle (juice volume and trypsin activity) in which food was offered in preruminant calves. No gastric or intestinal phase was observed in either group of calves. In conclusion, biological cycles of the gastrointestinal trac t are present in both preruminant and ruminant calves, and these cycle s evolve along with the change from liquid to solid food.