DIA-Based Proteomics Analysis Revealed the Impact of Dietary l‑Arginine Supplementation on Meat Protein in Mongolian Sheep through the Nitric Oxide Signaling

The longissimus thoracis (LT) muscle was collected from 12 Mongolian sheep fed either a basal diet (group C) or the basal diet supplemented with 1% l-arginine (group A) for 3 months. l-arginine significantly improved loin muscle area and meat tenderness and enhanced nitric oxide synthase (NOS) enzymatic activity as well as nitric oxide (NO) and NOS gene expression. DIA-based proteomics analysis revealed that the differentially abundant proteins were predominantly enriched in biological functions and metabolic pathways associated with skeletal muscle development and protein metabolism, which showed significant associations with the NO signaling pathways. The results of the PPI network analysis indicated a close interaction among skeletal-muscle-related proteins, which may influence mitochondrial electron transport chain (ETC) function via the NO signaling pathway. In conclusion, supplementing the diet with l-arginine can potentially influence skeletal muscle protein metabolism in Mongolian sheep, particularly affecting muscle contraction and the mitochondrial ETC via NO signaling pathways in LT muscle.