In-Depth Interpretation of Lamb-Related Protein Network Map for Muscle Formation Mechanism, Postmortem Meat Quality,...

Skeletal muscle fiber types contribute to lamb quality traits greatly. Longissimus thoracis (LT) and biceps femoris (BF) are two skeletal muscles in lambs. However, the key proteins and potential regulatory mechanisms shaping lamb skeletal muscle fibers and their impact on meat traits and proximate composition have not been clearly defined. In this study, LT and BF muscles were selected from nine Dorper (♂) × Small Tailed Han (♀) crossed ewe lambs raised on the same farm with similar body weight. The results revealed that BF muscle had a higher proportion of oxidized myofibers and gene expression of MyHC IIa compared to the LT muscle. Meanwhile, the BF muscle displayed lower shear force, b* value, crude fat, higher pH_24h value, and moisture (p < 0.05). Tandem mass tags (TMT)-based proteomic analysis identified 285 differentially abundant proteins, several of which were functionally associated with muscle structure development, glycolysis, and Ca^{2 +} regulation. These proteins may contribute to muscle fiber characteristics and meat quality properties. Functional annotation showed that glycolysis/gluconeogenesis and biological process such as carbohydrate metabolic process, glycolytic process, transition between fast and slow fiber, and ATP generation from ADP were significantly enriched. This study might provide new insights to improve meat attributes in the lamb industry.