Adaptation of pancreatic lipase to the amount and nature of dietary lipids in the growing pig.

The purpose of the present study was to examine the adaptation of pancreatic lipase to the amount and nature of dietary lipids in the growing pig. Thirty pigs were distributed into three groups of 10 animals each. They were fed the same amount (1.5 kg/pig/day) of either diet C (3.5% lard, 3.5% sunflower oil, 67.7% starch), diet L (21% lard, 33.2% starch) or diet SO (21% sunflower oil, 33.2% starch) for 12 days. The diets were isoenergetic and isonitrogenous. Pancreas weight relative to live-weight was highest in group L. The pancreatic lipid content of the latter group exceeded that of groups C and SO by 53 and 39%, respectively. The pancreatic protein content was similar in the three groups. The specific lipase activity of pancreatic tissue (U per mg of protein) in group SO was about 1.6-fold higher than that of group L and about 3-fold higher than that of group C (31.9, 19 and 11.6, respectively). Specific amylase activity was higher in animals of group C than in those of the other two groups (C : 1689; L : 1112; SO : 984), whereas no difference was observed in chymotrypsin activity. Specific trypsin activity was lowest in group L. These results confirm the adaptation of pancreatic lipase and amylase to their respective substrates. Furthermore, it appears that lipase activity was more or less affected by the degree of unsaturation of lipids and that it was much higher for the same amount of triacylglycerols when the latter were rich in unsaturated fatty acids. The mechanisms involved have not been determined yet, but the possible physiopathological consequences of the increased pancreatic lipid content observed in pigs receiving triacylglycerol-rich diets (including especially saturated fatty acids) should be considered.