Effects of Different Vegetable Oils on the Fatty Acid Metabolism Based on Whole Body Fatty Acid Balance Method and Gene Expression of Rainbow Trout (Oncorhynchus mykiss)

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The objective of conducted research was to analyze the growth performance, fatty acid (FA) metabolism and gene expressions related to polyunsaturated fatty acid (PUFA) metabolism in Oncorhynchus mykiss fed diets containing fish oil (FO), sesame oil (SO), linseed oil (LO) and olive oil (OO). Based on the results of the whole body FA balance method of the study, it was concluded that rainbow trout used n-3 PUFAs as energy and this affected the oxidation of n-6 long-chain polyunsaturated FAs (LC-PUFAs). Gene expression level of the Δ-6 desaturase was the lowest for FO and the highest for SO fed fish (P<0.05). Fish fed with OO had the lowest and fish fed with FO had the highest expression levels of elongase gene (P<0.05). The elongase (ELOVL5) transcription rate was higher in fish fed with FO diet and lower in fish fed with OO diet (P<0.05). In conclusion, this research indicated that the final n-3 PUFA ratio in fish fed with vegetable oil diets can be increased by the addition of 18:3n-3 and the decreased level of total dietary 18:2n-6, the balancing of dietary FAs with a proper content of saturated FA (SFA) and monounsaturated FA (MUFA) is substantial for the best growth.