Integrative Proteomic and Metabolomic Analyses Reveal Arginase-1-Mediated Nitrogen Metabolic Reprogramming Associated with Growth Advantage in Ronglai Binary Hybrid Pigs

Chinese native pig breeds have outstanding advantages in meat quality and adaptability but often exhibit slower growth and lower feed efficiency, limiting their commercial utilization. How to improve the growth efficiency of local pigs while maintaining their excellent characteristics through hybridization and mechanism analysis is the key to improving the quality and efficiency of the current industry. This study systematically evaluated the growth advantage of Ronglai binary hybrid pigs (RS, derived from Rongchang × Laiwu crosses) and integrated proteomic and metabolomic analyses to uncover the underlying metabolic mechanisms. Compared with purebred Rongchang pigs (RR), RS pigs showed a significantly higher average daily gain (553 vs. 454 g/d) from 85 days of age to the 90 kg body weight stage, representing a 21.8% improvement. Integrated multi-omics analysis revealed marked downregulation of arginase-1 (ARG1) protein in RS pigs, accompanied by decreased ornithine levels and elevated amounts of arginine-containing dipeptides. The elevated plasma NOx levels observed in RS pigs suggest that arginine accumulation may activate the NOS pathway. This reprogramming of nitrogen metabolism is associated with improved dietary nitrogen retention and utilization, thereby potentially directing more nutrients toward growth. While our findings provide a link between the growth advantage of this local pig cross and ARG1-mediated nitrogen metabolic remodeling, we acknowledge that to formally distinguish between heterosis and additive genetic effects, a control group of pure Laiwu pigs needs to be included.