Integrated Transcriptomics and Targeted Metabolomics Approaches: Comparative Analysis of the Ileum in Neonatal Piglets with Different Birth Weight

This study was conducted to elucidate the molecular and metabolic differences in ileal development according to birth weight in neonatal piglets. A total of 126 neonatal piglets born from Yorkshire × Landrace × Duroc crossbred sows were used, and the top 5% (H group, 1.77 ± 0.02 kg) and bottom 5% (L group, 0.72 ± 0.03 kg) of birth weights were selected for analysis. Ileal tissues were collected for transcriptomic (RNA-seq) and targeted metabolomic (GC–MS) analyses, and selected genes were validated using RT-qPCR. A total of 112 differentially expressed genes (DEGs) were identified, among which RFC3, PCNA, MCM3, MCM10, AURKA, AURKB, CCNB2, CCNA2, CCNF, and SI were significantly upregulated in the H group (p < 0.05). These genes were mainly involved in pathways related to DNA replication, cell division, and nutrient digestion and absorption. In addition, metabolomic analysis revealed that pyruvic acid concentrations were significantly higher in the H group (p < 0.05), indicating the activation of energy metabolic pathways. These results indicate that high-birth-weight piglets possess a genetic foundation for enhanced cellular proliferation and energy metabolism, and they further highlight potential molecular targets for improving growth performance and intestinal development in low-birth-weight piglets.