Dietary Methionine Affects Lipid Metabolism and Ferroptosis-Related Responses to Modulate Oxidative Stress Induced by High-Lipid-Diet in Golden Pompano (Trachinotus ovatus)

This study investigated the effects of high-lipid diets (HLD) with methionine (Met) supplementations on golden pompano (Trachinotus ovatus). T. ovatus (initial weight 82 ± 0.04 g) were fed with a normal lipid control diet (11.30% crude lipid and 1.04% Met, NLM) and HLDs (18% crude lipid) supplemented with varying Met levels (1.04%, 1.14%, 1.24%, 1.34%, 1.44%, 1.54% and 1.64%) namely HLM1, HLM2, HLM3, HLM4, HLM5, HLM6 and HLM7, respectively. After 56 days of feeding trial, the growth performance such as weight gain rate was significantly elevated in the HLM3 (p < 0.05). The liver lipid droplets area, sum of n-3 and n-6 poly-unsaturated fatty acids and fatty acid synthesis genes were elevated in the HLM1 and HLM7, while the genes for lipid breakdown were elevated in the HLM3. Based on the groups NLM, HLM1, and HLM3, the transcriptome sequence data revealed critical associated lipid metabolism, classic antioxidant pathway nrf2 and ferroptosis markers were influenced by Met and higher lipid. The fish livers in HLD groups with lower or higher Met showed the phenomenon of lipid oxidation obviously, while the reactive oxygen species and malondialdehyde were considerably lowered in the liver of fish in group HLM3 (p < 0.05). The hepatic Met was significantly reduced while cysteine was elevated in the HLM3 compared to HLM7 (p < 0.05). Fe and ferroptosis inducers were significantly upregulated in the liver of HLM1 and HLM7. HLM3 elevated anti-ferroptosis and anti-inflammation markers. In conclusion, Met inclusion in the HLD was associated with nrf2/keap1 and critical anti-ferroptosis-related transcriptional responses and regulated lipid metabolism in T. ovatus. The quadratic regression model revealed the optimal dietary Met in the HLD as 1.32%, which will help formulators make more rational and effective use of dietary lipid to support the better growth of golden pompano.