Combined Metabolomic and Transcriptomic Analysis Identifies Metabolic Signatures and Networks Associated with Semen Quality in Geese.

Semen quality is a critical determinant of male fertility in poultry, yet the testicular metabolic and molecular mechanisms underlying seminal traits in geese remain poorly understood. This study aimed to characterize the testicular metabolomic and transcriptomic profiles of Zhedong white geese with divergent semen quality, and to identify key regulatory pathways and candidate genes influencing semen quality. Untargeted metabolomics and RNA sequencing were performed on testicular tissues from geese with high (H) and low (L) semen quality. Serum hormone measurements revealed significantly increased testosterone (T) and decreased follicle-stimulating hormone (FSH) levels in the H group compared with the L group (p < 0.05). Metabolomic analysis identified 207 differential metabolites (DEMs), which were significantly enriched in glycosylphosphatidylinositol (GPI)-anchor biosynthesis, the citrate (TCA) cycle, and alanine, aspartate, and glutamate metabolism. Integrated transcriptomic and metabolomic analyses, combined with KEGG Markup Language (KGML) network analysis, revealed a candidate regulatory network involving potential metabolites (arachidonic acid, pyruvic acid, fumaric acid, malic acid and beta-alanine), signaling pathways (the citrate (TCA) cycle, arginine biosynthesis, ABC transporters, glycine/serine/threonine metabolism, and efferocytosis), and candidate genes (PLCB1, PLCB2, NT5C1A, TAT, LOC106042968 and ABCG8). Notably, PLCB1, which was significantly up-regulated in the H group, emerged as a candidate gene of particular interest that may be implicated in the regulation of metabolic pathways underlying semen quality in ganders. These findings provide novel insights into the testicular metabolic and transcriptomic determinants of semen quality in geese, and implicate PLCB1 and associated pathways as potential targets for improving male fertility in poultry.