Vertebral lipid composition in haddock (Melanogrammus aeglefinus L.) and Atlantic halibut (Hippoglossus hippoglossus )

The main objective of the study was to evaluate and compare lipids in the vertebrae column of Atlantic halibut and haddock reared under controlled conditions. The study therefore aimed at ascertaining if the bones of these fish species were oil-filled and to qualitatively and quantitatively analyse the composition of these lipids.; The major lipid profiles of the vertebrae column of haddock Melanogrammus aeglefinus L. and Atlantic halibut Hippoglossus hippoglossus were identified and compared to the respective profiles in the flesh and feeds of the fish. Methods of cutting bones into smaller sections before lipid extraction to maximize recovery of lipids were also developed.; The halibut bones were found to be more ossified than those of the haddock and had wider and deeper hollows filled with lipids. Haddock vertebrae had an average lipid content of 0.81+/-0.4% (w/w wet weight basis); halibut vertebrae on the other hand contained an average of 20.59+/-0.9% (w/w wet weight basis) lipid. Haddock had leaner muscle as compared to halibut. The composition of total lipid in the fish bones and muscle showed phospholipids (PL) to be the principal lipid class in the leaner tissues of haddock, while the triacylglycerides (TAG) formed the major class in halibut bones and muscle, which had a higher percentage lipid content. The phospholipid content of the haddock feed was higher than in the halibut food, and TAG was higher in halibut feed.; Polyunsaturated fatty acids were dominant in the haddock tissues as well as in the feed, while in halibut the monounsaturated fatty acids (MUFA) dominated while the saturated fatty acids (SFA) were least abundant in most of the sample lipids except haddock flesh. Generally, the fatty acid (FA) profile of the haddock feed was reflected in the lipid class and composition in the tissues, while in halibut lipid profiles in tissues were not closely reflective of their diet.; Palmitic acid (16:0) formed the largest part of the saturates in the tissues of fish samples. This fatty acid constituted an average of 20.3% (w/w, wet weight basis) and 9.52% of haddock flesh and vertebrae respectively, while forming 16.1% of FA in the vertebrae column of halibut. The fish tissues also contained appreciable levels of stearic acid, 18:0, and myristic acid, 14:0. The most abundant MUFA in the tissues of fish was identified to be 18:1o9. Levels of 18:2o6, 20:5o3 and 22:6o3 were appreciably high in the fish tissues.; There was a general positive correlation between the FA in the feeds and tissues of the fish samples suggesting an increase in the levels of the FA in the tissues as levels increased in their diet. Correlation coefficients between the FA levels in the vertebrae column and flesh were also positive. The levels of various FA in halibut flesh correlated more closely with levels in the bone as compared with correlation between the haddock bones and flesh. Correlation coefficients between FA of halibut bone versus feed and halibut flesh versus feed were better than in the corresponding correlations in haddock tissues and feed.; The phosphorus content of haddock vertebrae, 23.33+/-0.1% (w/w, dry weight basis) in this study, higher than in the halibut, 12.29+/-0.1%. Comparison of percentage inorganic phosphorus contents of the vertebrae with PL in the fish species suggested an increase in percentage PL with increase in the percentage phosphorus in the bone.