Placental multi-omics profiling reveals breed-related molecular differences associated with porcine reproductive performance.

Reproductive performance is a key determinant of pig production, yet the placental molecular characteristics associated with breed-related reproductive differences remain incompletely understood. We compared Landrace sows, a highly prolific European commercial breed, with Chuanzang black sows, a Chinese local composite breed with lower reproductive performance. Term placental tissues were collected from 12 sows, with three sows in each breed × parity group: Chuanzang black parity 2, Landrace parity 2, Chuanzang black parity 5, and Landrace parity 5. One placenta per sow was analysed by integrated transcriptomic, proteomic, and metabolomic profiling. Landrace sows showed higher total litter size, birth litter weight, weaning litter weight, and placental efficiency than Chuanzang black sows at both parities. Multi-omics analyses revealed breed-related differences in placental molecular profiles. Compared with placentas from Chuanzang black sows, placentas from Landrace sows showed stronger representation of extracellular matrix organisation, cell adhesion, and metabolic regulation pathways, including ECM-receptor interaction and focal adhesion. By contrast, placentas from Chuanzang black sows showed stronger enrichment of immune- and inflammation-related pathways than placentas from Landrace sows. Cross-omics integration indicated stronger transcript-protein concordance and more differential metabolites at parity 2 than at parity 5. Vitamin B6 metabolism was the most consistent pathway detected across the three omics layers, with pyridoxal kinase identified as a candidate molecular feature within this pathway. These findings suggest that breed-related reproductive differences are associated with coordinated variation in placental structure, immune regulation, and metabolic function, and provide candidate molecular features for further validation.