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Abstract

Black Sea trout (Salmo trutta labrax Pallas,1811) fed with diets based on 100% fish oil (FO), 67-33%, 50-50% and 33-67% soybean oil-linseed oil (SO-LO) during 90 days were affected in terms of weigth gain, specific growth rate, feed conversion ratio and hepatosomatix index significantly (P<0.05) while the survival rate was not affected at all. Tissue fatty acid profiles of the individuals were affected by the degree of dietary treatments (P<0.05). For instance, the highest linoleic acid (18:2n-6, LA) content of the muscle and liver tissues were exhibited in the group fed with 67-33 % SO-LO diet, where the highest linolenic acid (18:3n-3, LNA) was detected in the group fed with 33-67% SO-LO diet (P<0.05). In contrast to linoleic and linolenic acids, the highest values of palmitic (18:0), eicosepentaoneic (20:5n-3, EPA) and docohecsaenoic acids (22:6n-3, DHA) were indicated in group fed with fish oil based diet (P<0.05). Gene expression of desaturase in the muscle and liver tissues of individuals fed with 33-67% SO-LO included feeds were higher than those fed with FO. Similarly, gene expression of elongase both in the liver and muscle in individuals fed with (50-50% SO-LO, 33-67% SO-LO) and (50-50% SO-LO, 67-33% SO-LO) respectively were higher than those fed with FO. As a result, it was determined that use of 50-50% SO-LO in Black Sea trout diets is acceptable without an adverse effect on growth and feed conversion, and also this species have a capability of conversion 18:2n-6 to 20:4n-6 and 18:3n-3 to 22:6n-3.