Dietary Polyunsaturated Fatty Acid Supplementations Could Significantly Promote the Δ6 Fatty Acid Desaturase and Fatty Acid Elongase Gene Expression, Long Chain Polyunsaturated Fatty Acids, and Growth of Juvenile Cobia

Abstract

The experiment investigates the effect of different dietary polyunsaturated fatty acid (PUFA) supplementations on the gene expression of key enzymes for biosynthesizing long chain PUFA (LC-PUFA), LC-PUFA formation, and growth performance of juvenile cobia (Rachycentron canadum). It is found that dietary linolenic (LNA) and linoleic acids (LA) supplementations could significantly promote the expression of △6 fatty acid desaturase (FADS2) and fatty acid elongase (ELOVL5) genes in the brain, liver, and muscle of the juveniles; different dietary PUFA supplementations can significantly promote the growth performance and increase the LC-PUFA in the above organs/tissues of the juveniles; the optimum n-3/n-6PUFA ratio was 0.63 in SO + FO diet, in which n-6PUFAs was 27.4% and n-3PUFAs 17.4% in the diet, with the supplementation of 3% fish oil and 3% safflower oil. Practical Applications: Cobia is a new species with high econimic value and is developing rapidly. The LC-PUFA can promote the development, functions of nerves and cell members in fish juveniles, which are an important period of fish. Can juvenile cobia biosynthesize LC-PUFA from C18:2n-6 and C18:3n-3? The results show that dietary LNA and LA supplementations significantly promoted the FADS2 and ELOVL5 gene expression, fatty acids, and growth of cobia juveniles. Dietary LNA and LA supplementations could significantly promote the expression of Δ6 fatty acid desaturase (FADS2) and fatty acid elongase (ELOVL5) genes in the brain, liver, and muscle of juvenile cobia.