Untargeted metabolomics analysis reveals comparative meat quality of different muscles and the impact of Saline-alkali land feeding on Dolang sheep (Ovis aries)

As an important meat resource, lamb has a wide consumer market worldwide. Dolang sheep of Xinjiang are renowned for their tender meat and unique flavor, and the quality of mutton is remarkably influenced by the saline-alkali environment. Therefore, this study aimed to explore the differences in meat quality between different parts of Dolang sheep and the meat quality under different rearing conditions in Shache and Bachu, Kashgar. By measuring the conventional nutritional content of mutton and key quality indicators, we found that the total amino acid content and crude protein in the leg muscle (LM group) of Dolang sheep were lower by 15.45% and 12.87% than those in the longissimus dorsi (LD group) (P < 0.05). The crude fat content in Dolang sheep from Shache (BS group) was 54.45% lower than that in Bachu (WS group) (P < 0.05), while the pH value was higher than the WS group (P < 0.001). Using LC-MS to detect mutton metabolites, we found that the strong correlation of metabolites suggests differences in nucleotide metabolism and energy production between the LD and LM groups. The downregulation of metabolites in the BS group is related to enhanced saccharometabolism. In contrast, the upregulation of carnitine derivatives in the BS group is linked to fatty acid metabolism and transport. Through KEGG pathway analysis, we further revealed the changes in metabolic activity of these differentially expressed metabolites under different rearing environments. The differential metabolites between the two groups were mainly enriched in metabolic pathways such as Purine metabolism、Arachidonic acid metabolism, and Pentose Phosphate Pathway, which are closely related to the crude fat content and pH value of mutton. The results of this experiment, focusing exclusively on the Dolang sheep breed and examining the effects of different rearing conditions, provide a scientific basis for optimizing breeding strategies and improving mutton quality. These findings also offer theoretical support for the sustainable development of the mutton industry, underscoring the significance of precise breeding environment management in enhancing mutton quality.