Transcriptomic analysis of differentially expressed genes associated with growth, meat quality, and fatty acid metabolism in Sunit lambs under varying rearing conditions

Pasture-based feeding is generally associated with superior meat quality, particularly in terms of favorable fatty acid profiles, whereas concentrate-based feeding typically promotes faster growth and higher productivity, albeit often at the expense of certain aspects of meat quality. Therefore, this study provides insights into the molecular mechanisms underlying meat quality variations in lambs raised under different feeding regimes. The findings are expected to contribute to optimized feeding strategies for balancing growth performance and meat quality in lamb production. This study aimed to evaluate the effects of concentrate and pasture feeding systems on carcass traits, meat quality, and the expression of genes related to muscle growth, development, and fatty acid metabolism in Sunit lambs. Twelve lambs (17.39 ± 0.59 kg) were used for the experiment. The results showed that pasture feeding reduced cooking loss, increased shear force, and significantly enhanced the content of polyunsaturated fatty acids in the longissimus thoracis muscle (LTM) of lambs (P < 0.05) compared to concentrate feeding. A total of 297 differentially expressed genes (DEGs) were identified in the LTM between the two feeding systems. Among them, CSRP3, MSTN, MYOD1, and MAP2K3 were found to be significantly associated with growth, muscle development, and fatty acid metabolism. These DEGs are involved in signaling pathways associated with muscle development and fatty acid metabolism, including myocyte proliferation, differentiation, mitogen-activated protein kinase, and peroxisome proliferators-activated receptor signaling. These pathways promote muscle growth, reduce fatty acid oxidation, and improve fatty acid composition, collectively enhancing the nutritional value of meat from pasture-fed lambs. This study offers novel insights into how feeding strategies modulate lamb meat quality at the molecular level and proposes candidate regulatory genes involved in muscle development and meat quality enhancement.