Integrative Metabolomic and Transcriptomic Analyses Reveal the Impact of Methionine Supplementation to Gibel Carp (Carassius auratus gibelio)

The experiment was conducted to evaluate the molecular mechanism of methionine supplementation on the growth of gibel carp. In the study, the following five groups were included: the control group (FM) was fed with a high-plant protein diet as basal diet, and four treatment groups were supplemented with 0.25% crystalline methionine (CM50), 0.50% crystalline methionine (CM100), 0.25% coated methionine (HM50) or 0.50% coated methionine (HM100), respectively. Each group consisted of four replicates of 25 fish each. The weight gain rate and specific growth rate of gibel carp in the HM100 group were significantly higher than the FM group. The hepatopancreas transcriptomic (n = 4) and metabolomic (n = 6) analysis for the FM group and HM100 group showed that the significantly differential metabolites mainly related to amino acid metabolism, protein digestion and absorption, and aminoacyl-tRNA biosynthesis. Additionally, some genes that were significantly different in these two groups were involved in energy metabolism and transmembrane transporter activity. Therefore, the improvement of fish growth by 0.50% coated methionine supplementation might be achieved through altering amino acid and energy-related metabolism in hepatopancreas, which provides new insights for understanding the impact of methionine on the growth of fish.