1. Pancreatic juice was collected from six pigs of 48 kg initial weight fitted with a collection catheter in the pancreatic duct and a return catheter in the duodenum.
2. Measurements of flow and composition of the juice were made during 24 h periods after adaptation to isonitrogenous diets based on barley, wheatings and fish meal (diet BWF) or starch, sucrose, casein, maize oil and cellulose (diet SSC), given in a change-over design. Measurements were also made during the periods of adaptation to a change from one diet to the other.
3. Mean flow-rates for pigs adapted to diets showed a highly significant four-fold difference between diets; values were 4962 ml/d for diet BWF and 1273 ml/d for diet SSC. The hourly volumes of juice were very variable and showed no clear response to feeding and no consistent diurnal pattern for either diet.
4. There were no significant differences between diets in the specific activities of the proteases. Average values were (units/nig protein) trypsin. (EC 22.214.171.124) 29·6, chymotrypsin (EC 126.96.36.199) 7·7, carboxypeptidase A (EC 188.8.131.52) 0·65, carboxypeptidase B (EC 184.108.40.206) 1.6. The total output of each tended to be higher with diet BWF than with diet SSC. The specific activities and tolal outputs of α-amylase (EC 220.127.116.11) and lipase (EC 18.104.22.168) were significantly higher for diet BWF than for diet SSC; specific activities for the two diets respectively were: (units/mg protein) α-amylase 95·6 and 42·3, lipase 59·0 and 14·5.
5. The higher daily volume of juice with diet BWF was associated with significantly (but only slightly) higher levels of both sodium and potassium, compared with diet SSC.
6. The results are discussed in relation to previous studies on digestion at this Institute, in which pigs with intestinal cannulas were given the same diets.