Mass spectrometry-based metabolic profiling for identification of biomarkers in serum related to the change of laying ducks in different physiological periods

Eggs are a major animal protein source for humans. Egg formation is a complex process involved in coordinating various tissues and organs, while blood is necessary for gonad differentiation and egg formation. In this study, non-targeted metabolomics technology was employed to determine the serum metabolites at the time point of 70 days (before laying period, T0), 130 days (pre-laying period, T1), 300 days (peak laying period, T2), and 340 days (post laying period, T3) in female ducks, to provide comprehensive metabolic profiling in reflecting the overall temporal changes. The results showed significant differences in the metabolites of different comparison groups (T0 vs. T1, T2 vs. T3, and T0 & T1 vs. T2& T3), supporting the main physiological responses in ducks are differential among laying periods. L-Aspartic Acid, Biotin, and Thyroxine can be considered the potential biomarkers related to sexual maturity. L-Lysine, Lumichrome, Thiamine, Riboflavin, and Pyridoxine may be biomarkers related to egg formation. Sorbitol, Isorhamnetin, Naringenin, and Hydroxykynurenine were the biomarkers associated with the decline of egg production. In addition, the Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway analysis showed that sexual maturity was mainly involved in the biosynthesis of secondary plant metabolites, Tricarboxylic Acid Cycle, Mineral absorption, pentose phosphate pathway, and Oxocarboxylic acid metabolism. Egg formation disturbed amino acid metabolism, vitamin metabolism, and carbohydrate metabolism. The neuroactive ligand-receptor interaction pathway may affect egg production. These findings can detect the different physiological statuses in female ducks and provide a theoretical basis for increasing egg production, and ensuring sustainable farming.HighlightsThe main physiological responses in ducks are differential among laying periods.3, 6, and 4 biomarkers related to sexual maturity, the formation of the egg, and the decline of egg production, respectively.Sexual maturity was mainly involved in the biosynthesis of secondary plant metabolites, Tricarboxylic Acid Cycle, Mineral absorption, pentose phosphate pathway, and Oxocarboxylic acid metabolism, and egg formation disturbed amino acid metabolism, vitamin metabolism, and carbohydrate metabolism. while the neuroactive ligand-receptor interaction pathway may affect egg production. The main physiological responses in ducks are differential among laying periods. 3, 6, and 4 biomarkers related to sexual maturity, the formation of the egg, and the decline of egg production, respectively. Sexual maturity was mainly involved in the biosynthesis of secondary plant metabolites, Tricarboxylic Acid Cycle, Mineral absorption, pentose phosphate pathway, and Oxocarboxylic acid metabolism, and egg formation disturbed amino acid metabolism, vitamin metabolism, and carbohydrate metabolism. while the neuroactive ligand-receptor interaction pathway may affect egg production.

禽蛋是人类重要的动物蛋白来源。产蛋过程是一项涉及多组织、多器官协同调控的复杂生理活动，而血液为性腺分化与产蛋形成所必需。本研究采用非靶向代谢组学（non-targeted metabolomics）技术，对70日龄（开产前，T0）、130日龄（产蛋预备期，T1）、300日龄（产蛋高峰期，T2）及340日龄（产蛋后期，T3）的母鸭血清代谢物进行检测，以获取全面的代谢谱特征，反映产蛋周期内的整体时序性代谢变化。
结果显示，不同比较组（T0 vs T1、T2 vs T3及T0&T1 vs T2&T3）的血清代谢物均存在显著差异，表明母鸭在不同产蛋阶段的核心生理反应存在显著分化。其中，L-天冬氨酸、生物素与甲状腺素可作为与性成熟相关的潜在生物标志物；L-赖氨酸、卢米黄素（Lumichrome）、硫胺素、核黄素与吡哆醇可作为与产蛋形成相关的潜在生物标志物；山梨醇、异鼠李素、柚皮素与羟基犬尿氨酸则为与产蛋量下降相关的潜在生物标志物。
此外，京都基因与基因组百科全书（Kyoto Encyclopaedia of Genes and Genomes, KEGG）通路分析结果表明，性成熟主要涉及植物次生代谢物生物合成、三羧酸循环、矿物质吸收、磷酸戊糖途径及含氧酸代谢；产蛋形成则扰动了氨基酸代谢、维生素代谢与碳水化合物代谢；而神经活性配体-受体相互作用通路可能对产蛋性能产生影响。
本研究结果可用于精准鉴别母鸭的不同生理状态，为提升产蛋量、保障养殖业可持续发展提供理论支撑。

**研究亮点**：
1. 母鸭在不同产蛋阶段的核心生理反应存在显著差异；
2. 分别鉴定出与性成熟、产蛋形成及产蛋量下降相关的3种、6种及4种潜在生物标志物；
3. 性成熟主要参与植物次生代谢物生物合成、三羧酸循环、矿物质吸收、磷酸戊糖途径及含氧酸代谢，产蛋形成会扰动氨基酸代谢、维生素代谢与碳水化合物代谢，且神经活性配体-受体相互作用通路可能影响产蛋性能。