Effects of Alternative Oil Sources on Growth Performance, Lipid Metabolism and mRNA Level of Some Genes in Juvenile Black Sea Trout (Salmo trutta labrax Pallas, 1811)

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.