Juvenile In Vitro Embryo Transfer (JIVET) can shorten generation intervals but is limited by large individual variation in superovulation response. To elucidate metabolic mechanisms and identify serum biomarkers, 18 female Tan lambs (4-8 weeks) received uniform superovulation and were classified into high, medium, and low production groups based on follicle counts and oocyte recovery. Pre- and post-superovulation serum samples were analyzed by LC-MS/MS untargeted metabolomics. A total of 1,899 metabolites were identified. Pre-superovulation, metabolic profiles of the high- and low-yield groups were clearly separated, with differential metabolites enriched in amino acid biosynthesis and glycine-serine-threonine metabolism. Post-superovulation, enrichment shifted to phenylalanine and linoleic acid metabolism. Intersection analysis revealed eight lipid metabolites consistently upregulated in the order high > medium > low at both pre- and post-superovulation stages, including medium-chain fatty acids (lauric, caprylic, capric acid), a bile acid (taurochenodeoxycholic acid), three lysophosphatidylcholines, and a sphingolipid (ganglioside GA2). Among these, lauric acid, taurochenodeoxycholic acid, and LysoPC(22:1(13Z)) showed significantly higher abundance in high-yield lambs. These findings indicate that superovulation efficiency is closely linked to basal lipid metabolism capacity. The eight lipid metabolites may serve as candidate serum biomarkers for predicting JIVET donor potential, providing a theoretical basis for pre-selection and advancing the understanding of metabolism-reproduction axis regulation.