COMPARATIVE ANALYSIS OF GROWTH, MUSCLE NUTRIENT COMPOSITION, AND SKIN TRANSCRIPTOME IN F1 HYBRIDS OF CTENOPHARYNGODON IDELLA WITH TWO DIFFERENT BODY COLORS

To investigate the growth performance, muscle quality, and expression characteristics of body color-related genes in the F1 generation of three grass carp (<italic>Ctenopharyngodon idella</italic>) families with two different body colors, this study established three F1 families: <italic>Ctenopharyngodon idella</italic> var. gold (♀) × <italic>C. idella</italic> var. gold (♂) (GG), <italic>C. idella</italic> var. gold (♀) × <italic>C. idella</italic> (♂) (GB), and <italic>C. idella</italic> (♀) × <italic>C. idella</italic> (♂) (BB), and systematically evaluated their growth traits, muscle quality, and skin transcriptome profiles through morphometric, nutritional, and RNA-seq analyses. Key findings revealed that: (1) The GG family exhibited significantly higher weight gain rate and specific growth rate compared to the BB and GB families (<italic>P</italic>&lt;0.05), showing a trend of GG&gt;BB&gt;GB; (2) Muscle composition analysis revealed significantly higher moisture and lower crude fat content in the GG family (<italic>P</italic>&lt;0.05), along with elevated levels of eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA), total amino acids (TAA), total essential amino acids (TEAA), and total delicious amino acids (TDAA) compared to BB and GB families (<italic>P</italic>&lt;0.05); (3) Protein quality assessment indicated higher amino acid score (AAS), chemical score (CS), and essential amino acid index (EAAI) in GG family than those in BB and GB families; (4) transcriptome analysis identified differentially expressed genes (DEGs) between GG/BB and GB/BB, which were significantly enriched in GO terms such as ATP metabolic process, mononucleotide metabolic process, purine nucleoside monophosphate metabolic process, mitochondrion, heme binding, tetrapyrrole binding, and oxidoreductase activity, as well as pathways including oxidative phosphorylation and cell adhesion molecules. DEGs related to body color formation in grass carp, such as <italic>cdk4, mt-atp6, csf1r, xdh,</italic> and <italic>sox9b,</italic> were identified. In conclusion, the GG family exhibits superior growth performance and nutritional profile compared to the GB and BB families, and the identification of body color-related genes provides a scientific basis for deciphering the molecular mechanisms and advancing the selective breeding of golden grass carp.