Dietary supplementation of vitamin E and citric acid could significantly promote the relative expression of PPARα and aconitase genes, concentration of polyunsaturated fatty acids, antioxidant enzyme activities, and growth of juvenile cobia

The experiment was to study the effect of different dietary vitamin E (VE) and/or citric acid (CA) supplementation on the peroxisome proliferator-activated receptor alpha (PPAR alpha) and aconitase (ACO) gene expression, fatty acids, antioxidant enzyme activities, and growth of juvenile cobia (Rachycentron canadum). Seven groups of cobia juveniles in triplicate were cultured in tanks using filtered and aerated seawater. The juveniles were fed twice a day using 7 specific diets: control diet (DO) without supplementation; Diets 1 to 6 (D1 to D6) were supplemented with CA 0, 12, 12, 6, 3, 1.5 g and VE 100, 0, 100, 75, 50, 25 IU per kg of dried feed, respectively. The juveniles were fed for 12 weeks and their liver, muscle, and serum were sampled randomly for analysis in weeks 0 and 12. The results showed that the supplementation of VE plus CA could significantly promote the relative mRNA expression of ACO and PPARa genes, concentration of polyunsaturated fatty acids (PUFAs), activity of antioxidant enzymes, and growth of juvenile cobia. The effect of both dietary VE plus CA supplementation on the above indexes was significantly greater (P < 0.05) than a single VE (D1) or CA (D2) supplementation. The optimum diet was D5, with a VE of 50 IU and a CA of 3 g supplementation per kg of dried feed in the tested diets.