Temperature-driven metabolic shifts in duck egg components during early embryogenesis: from diapause to active developmental phase

Embryonic diapause, a survival strategy observed in birds such as wild ducks (where entire clutches may suspend development), allows embryos to delay growth under suboptimal conditions. In commercial practices, this trait is harnessed to synchronise hatching with market schedules, maximising production efficiency. We propose that temperature-driven reactivation of diapause involves metabolic responses linked to dynamic small molecule profiles in yolk and albumen, potentially regulating embryonic resumption. Using 12 duck eggs divided equally into experimental and control groups, we conducted untargeted metabolomics to profile metabolic dynamics during the 48-h diapause-to-embryogenesis transition across pre- and post-incubation phases. Differential metabolite analysis in yolk and albumen was integrated with KEGG pathway enrichment to identify functional shifts linked to embryonic reactivation. In our study, we identified 17 and 22 differentially abundant metabolites in yolk and albumen, respectively, with upregulated Arachidonic acid and downregulated N-acetylserotonin in yolk and upregulated ketoleucine in albumen, implicating roles in embryonic development via signalling, amino acid metabolism and antioxidant functions. The KEGG analysis uncovered enriched pathways, including Tryptophan metabolism, Branched-Chain Amino Acids (BCAA) biosynthesis and ATP-binding cassette (ABC) transporters, which may play pivotal roles in initiating duck embryo development. We speculate that tryptophan and branched-chain amino acid metabolism influence embryo development through protein synthesis regulation, combined with ABC transporter-mediated nutrient allocation during temperature shifts. The enrichment of Arachidonic acid in Gonadotropin-releasing Hormone (GnRH) signalling pathway might suggest its role in critical processes. Our findings may help refine incubation practices and breeding outcomes by understanding duck embryo diapause mechanisms.