Abstract

Present study was conducted to accurately evaluate the optimal dietary lipid level in golden pompano ( Trachinotus ovatus ) diets combining phenotypic responses and transcriptomics analysis. Fish with initial body weight 27.65 g ± 0.17 g were fed diets with six lipid levels (9.13%, 10.59%, 12.12%, 14.98%, 16.25%, 19.26%), respectively. Results showed that dietary lipid levels significantly altered the weight gain rate, specific growth rate protein efficiency ratio and reached the maximum when fish fed diet with 12.12% lipid. Proximate composition analysis indicated that body nutrients content were significantly improved by dietary lipid levels. Moreover, total glucose, triglycerides and high-density lipoprotein were also elevated by dietary lipid level. Transcriptomic analysis suggested that muscle growth regulation, hormone response, nutrient metabolism and immune response were more sensitive to dietary lipid levels. Further analyzed mechanisms, data demonstrated that dietary lipid levels could through nutrient sensing signaling pathways to regulate lipid metabolism. Meanwhile, Diet 3 (lipid level: 12.12%) had lower level mRNA expression of the key regulators in immune responses and antioxidant defense. Either too lower or too higher lipid in diet could trigger oxidative stress and immune responses. In conclusion, according to broken-line regression on WGR and SGR, the optimal lipid level for golden pompano were 11.28% and 11.20%, respectively. Present study provided the optimal requirement of dietary lipid level based on a comprehensive method.