Lipid digestibility and metabolism in Atlantic salmon (Salmo salar) fed medium-chain triglycerides

Atlantic salmon with an average initial weight of 180 g were fed either a control diet containing 25% fish oil or a diet with 15% fish oil and 10% of an oil based on medium-chain fatty acid triglycerides (MCTs). The fish were kept in tanks supplied with saltwater for 65 days. The fish group with the lowest feed intake determined feeding level in the remaining groups. Exchanging 1/3 of the dietary fat with a MCT oil affected fatty acid digestibility and lipid metabolism. The medium-chain fatty acids (MCFAs) were highly digestible, 99.6% for 8:0 and 96.7% for 10:0, and were absorbed mainly in the pyloric region. However, MCT seemed to reduce pyloric absorption of other fatty acids. In the pyloric region, only 5.4% of 22:6n - 3 was absorbed in fish fed MCT, whereas 32.0% of this fatty acid was absorbed in fish fed the control diet. Fat percentage in muscle was reduced from 6.1% in controls to 4.4% in MCT fed fish. Dietary MCTs were found to increase the percentage of C18:1 fatty acids in the liver and reduce mitochondrial beta-oxidation of C16:0 in this organ. (C) 2000 Elsevier Science B.V. All rights reserved.