Effects of vegetable oil replacement on intramuscular fat deposition and flesh quality of large yellow croaker (Larimichthys crocea) juveniles

The present study was conducted to investigate the effects of vegetable oil replacement on intramuscular fat deposition and flesh quality of large yellow croaker (Larimichthys crocea) juveniles. Five experiment diets were formulated with different vegetable oils substituting fish oil (fish oil group: FO, soybean oil group: SO, linseed oil group: LO, palm oil group: PO and olive oil group: OO). Juvenile large yellow croaker with an initial size of 6.04 ± 0.08 g were selected and randomly assigned to seawater cages (4 m × 4 m × 4 m). Each diet treatment was set up for three replicates, and 60 juvenile large yellow croaker were cultured in each replicate to carry out the experiment. The formal experiment lasted for 10 weeks, and the cultured fish was hand fed to apparent satiation twice daily at 6:00 am and 5:00 pm. During the experiment, the water temperature ranged from 19.3 °C to 22.8 °C, the salinity ranged from 25.6 to 29.9‰, and the dissolved oxygen level ranged from 6.3 to 7.4 mg/L. Results showed that compared with the FO group, the muscle triglyceride in SO, LO and PO group was significantly decreased (P < 0.05), which led to the significant up-regulations of muscle hardness, chewiness and gumminess (P < 0.05). SO, LO and PO treatments significantly up-regulated the gene expression of pparα and cpt1b compared with FO treatment (P < 0.05). Meanwhile, SO, LO and PO groups also enhanced the activity of muscle citrate synthase. Additionally, gene expression of pgc1-α, nrf1 and tfam was significantly up-regulated in the SO group compared with the FO group. The results of the muscle transcriptome indicated that compared with the FO group, the SO group could significantly increase the gene expression of prkag2 and the protein expression of p-AMPK/AMPK (P < 0.05). In conclusion, replacing fish oil with different vegetable oils could affect muscle sensory quality indices of juvenile large yellow croaker by changing intramuscular fat deposition, which might be due to the regulation on muscle mitochondrial biogenesis and fatty acid β-oxidation.