Effect of dietary canola oil and its degree of oxidation on exocrine pancreatic secretions in growing pigs.

Four barrows, average initial weight 35 kg, were fitted with permanent pancreatic re-entrant cannulas and used to determine the effect of level and quality of dietary fat on exocrine pancreatic secretions. The pigs were fed four corn starch-based diets that contained 15% crude protein from isolated soy protein. Diet 1 contained no canola oil (C-0); diet 2, 15% canola oil (C-15); diet 3, 15% canola oil that was heated under vacuum at 180 degrees C for 12 h (C-15/12); diet 4, 15% canola oil that was heated under vacuum at 180 degrees C for 24 h (C-15/24). Heat treatment resulted in a 4- to 5-fold increase in the content of malonaldehyde which is derived from the oxidation of fatty acids and which is closely related to odour and rancidity in lipids. The experiment was carried out according to a 4 x 4 Latin square design. The pigs were fed twice daily, at 08:00 and 20:00 h, 900 g each meal. Following an adaptation period of 7 d, pancreatic juice was collected continuously for 24 h at 2-h intervals from 08:00 on d 8 until 08:00 on d 9 and from 08:00 on d 10 until 08:00 on d 11 during each experimental period. The volume of secretion of pancreatic juice peaked 6-10 h postprandially and was similar (P > .05) during day (08:00-20:00 h) and night (20:00-08:00 h). Replacement of 15% starch by 15% canola oil resulted in a decrease (P < .05) in the secretion of alpha-amylase and an increase (P < .05) in the secretion of lipase. The inclusion of oxidized fat caused a further increase (P < .05) in total lipase activities. It can be concluded that the exocrine pancreas is able to adapt to variations in the level and quality of dietary lipids.