Proteinomics Analysis Indicated That Mitochondrial Energy Metabolism in Skeletal Muscle Tissue Was Negatively Correlated with Feed Efficiency in Pigs

Feed efficiency (FE) trait is a highly important economic trait in pig production. Investigating the molecular mechanism of FE is essential for trait improvement. In this study, the proteinomics of skeletal muscle tissues of three pigs with extremely high FE and three pigs with extremely low FE were investigated using iTRAQ approaches. A total of 1780 proteins were identified, in which 124 differentially expressed proteins were found between high- and low-FE pigs. Among these proteins, 74 were up-regulated and 50 were down-regulated in the high-FE pigs. Functional analysis indicated that mitochondrial energy metabolism was highly important for FE pigs. All 25 differentially expressed proteins located in the mitochondria were down-regulated in the high-FE pigs; these proteins included 11 oxidativephosphorylation enzymes and 2 key enzymes of the tricarboxylic acid (TCA) pathway. Furthermore, the enzymes involved in the conversion of glucose to pyruvate were up-regulated in the high-FE pigs. The glucose–pyruvate–TCA–oxidativephosphorylation energy metabolism signaling pathway was finally identified to differ between high- and low-FE pigs. Therefore, we concluded thatmitochondrial energy metabolism in the muscle tissue was negatively correlated with FE in pigs, and glucose utilization was more efficient in the muscle tissue of high- FE pigs.