Transcriptomic and metabolomic analyses of the livers of high- and low-egg-producing pigeons

Egg production is an essential metric used to assess poultry reproductive efficiency. The liver, functioning as a vital metabolic organ, is integral to avian reproduction and the overall productivity of laying birds. In this research, we aimed to explore various aspects of the mechanisms behind egg production across different poultry species by conducting transcriptomic and metabolomic analyses, as well as integrated assessments, of liver tissues from high- and low-producing pigeons to investigate the biosynthesis processes and identify pivotal genes and metabolic pathways in the liver during egg production. There were 1380 differentially expressed genes (DEGs) identified between the low- and high-production groups. The low-production group had 670 upregulated and 710 downregulated genes. Five genes identified were linked to egg production in the transcriptome: PRLR, HMGCR, CDK6, PTGR1 and RBPJ. The pathways that were identified to be the most significant encompass cytokine-cytokine receptor interaction, PI3K-AKT and JAK-STAT signalling pathways. Of the 229 significantly differentially abundant metabolites (DAMs) identified, 71 were upregulated, and 158 were downregulated, of which forskolin, methionine, prostaglandin F2α and adenosine 5'-diphosphate emerged as key metabolites associated with reproduction. By integrating transcriptomic and metabolomic data, we uncovered correlations between specific DEGs and DAMs, revealing significant gene-metabolite pairs, namely, PRLR-prostaglandin F2α and PRLR-adenosine 5'-diphosphate, involved in egg production. The new knowledge substantially enhances our comprehension of the molecular distinctions in hepatic physiology of high- and low-producing pigeons and establishes a valuable theoretical framework for future investigations into the mechanistic basis of avian egg-laying performance.