| Summary: | The lipid composition in terms of component lipids and component acids - of farmed and wild Atlantic salmon (Salmo salar) was studied at various stages of their life cycle, up to and including sexual maturation. Lipids were extracted separately from flesh, liver and gonad organs for this study. The majority of samples examined in this work were from farmed salmon and to determine the influence of the diet on their lipid composition, a sample of the diet fed to farmed salmon was extracted and its lipids analysed. The dietary lipid is composed mainly of neutral lipids, particularly triacylglycerols, with minor amounts of polar lipids (phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl inositol and cardiolipin).The fatty acid composition of the dietary lipid components suggested that the dietary lipid was a mixture of vegetable oils, seed oils and. fish meal(s).The major neutral lipids of salmon tissues were triacyl-glycerols, cholesterol and cholesterol esters while the dominant polar lipids were phosphatidyl choline and phosphatidyl ethanolamine, with smaller amounts of cardiolipin, phosphatidyl inositol, phosphatidyl serine and spingomyelin. The major fatty acids present in all samples examined included saturated acids (mainly 16:0 accompanied by 14:0 and 18:0), monoene acids (16:1, 18:1 and 20:1, with lower levels of 22:1 and 24:1), the n-6 group of acids, of which only 18:2 and 20:4 are consistently noticeable, and, at a much higher level, the n-3 group of acids with 22:6 > 20:5 > 22:5 >> other members. Neutral lipids (mainly TG) were highest in the flesh and least in the liver where correspondingly polar lipids (PC and PE) were highest. Variations occurred in fatty acid composition in relation to lipid class and lipid site (flesh, liver and gonads). Phosphatidyl cholines had the highest proportion of saturated acids at all three sites, whereas triacylglycerols had the highest monoene and n-6 polyene acid content. The phospholipids had very high levels of n-3 polyene acids at all three ...
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