DIA-based quantitative proteomic insight of lamb meat quality: Tenderness and amino acid profile under different grazing intensities

The quality of lamb meat from natural pastures tends to be influenced by the pasture's condition. This study investigated the impact of grazing intensity on lamb meat quality, identifying moderate grazing as optimal for enhancing meat attributes such as higher a∗ 45min values, larger loin eye areas, reduced drip loss, and lower shear force. Proteins related to muscle structure (SLC4A1 and FMNL2) and metabolic enzymes (AKR1C1 isoform X1, PGFS, and Inmt) emerged as potential biomarkers for tenderness. Enriched differential metabolic pathways, particularly those associated with amino acid metabolism like tyrosine, arginine, and proline metabolism, were noted. Lambs under heavy grazing exhibited elevated levels of proline, which may lead to tougher lamb meat. Additionally, heavy grazing lambs showed increased levels of six key amino acids (arginine, glutamic acid, isoleucine, phenylalanine, proline, and tyrosine), the main mechanisms were activation of metabolic pathways, involving glycolytic enzyme (ALDOB) and gluconeogenic enzyme (FBP1) and few others metabolism enzymes (ADH1C, SULT1C4, ACAT2 and Aldh1l1). Oxidative stress and response to stress proteins (HP, CAT and RGN) were also participated in amino acid accumulation. The data reflected the vital role of metabolic enzymes in regulating lamb meat quality. • Grazing intensity altered tenderness and amino acid profile of lamb meat • Five proteins were identified as lamb meat tenderness biomarkers in proteomics •Amino acid variations resulted from oxidative stress proteins and metabolic pathways