Abstract:In order to study the change rule of nutrient substance in ovaries of female Alosa sapidissima at the late stage of development and improve the fertilization rate of eggs, the contents of amino acids, fatty acids, vitellogenin (VTG)and cathepsin D (CTSD)and their mRNA expression in the ovaries of female Alosa sapidissima at the stages Ⅳ and Ⅴ of gonadal development were compared and analyzed by biochemical analysis, enzyme-linked immunosorbent assay and fluorescence quantitative PCR. The results showed that the water content (75.73%) in stage Ⅳ ovary was significantly lower than that (90.64%) in stage V ovary, while the crude protein content (16.07%), crude fat content (2.86%) and crude ash content (1.28%) were significantly greater than those (5.83%, 1.25%, 0.81%) in stage Ⅴ ovary. Among the 18 amino acids detected in the ovaries of stages Ⅳ and Ⅴ, the content of glutamic acid was the highest (8.64% and 8.13%). Among the 8 essential amino acids, the contents of threonine, phenylalanine, lysine and tryptophan in stage Ⅳ were significantly higher than those in stage Ⅴ, and the first limiting amino acid of both was tryptophan. The total amino acid (TAA), semi-essential amino acid (HEAA) and total non-essential amino acid (NEAA) in stage Ⅳ were significantly higher than those in stage Ⅴ. A total of 19 fatty acids were detected in the ovaries of the two stages, and the contents of C17:0, C20:1n9, C20:4n6 and C20:5n3 in stage Ⅳ were significantly higher than those in stage Ⅴ; the contents of ∑ MUFA, ∑ PUFA, ∑ UFA, ∑ n3PUFA and EPA + DHA in stage Ⅳ were greater than those in stage Ⅴ, and ∑ UFA (70.54%) reached significant differences. The content of VTG in stage Ⅳ ovary was higher than that in stage Ⅴ ovary, but it was not significant, while the content of CTSD in stage Ⅳ ovary was significantly lower than that in stage Ⅴ ovary. The expression of VTG gene in stage Ⅴ ovary was significantly higher than that in stage Ⅳ, 13.88 times of that in stage Ⅳ, while the expression of VTG gene in liver was significantly lower than that in stage Ⅳ, accounting for 25% higher than that in stage Ⅳ. From stage Ⅳ to stage Ⅴ, CTSD mRNA expression showed down-regulation in the ovary and up-regulation in the liver, but none of them was significant. Therefore, under the current aquaculture conditions, the accumulation of nutrients in the ovary is uneven during the late development of the Alosa sapidissima, and it is recommended to appropriately adjust the feed formula, increase the ratio of limiting amino acids tryptophan, methionine, L-Phenylalanine and lysine and threonine with lower content, increase the ratio of polyunsaturated fatty acids C20:3n6, C20:4n6 (AA), C22:6n3 (DHA) and C20:5n3 (EPA), and decrease the ratio of C18:2n6c in order to ensure the balance of nutrients required for the late development of the ovary.