Differential Energy Metabolism in Skeletal Muscle Tissues of Yili Horses Based on Targeted Metabolomics and Transcriptomics Analysis

Skeletal muscle is the largest organ system in mammals. To investigate the differences in energy metabolism across various skeletal muscles in Yili horses, this study examined muscle fiber type distributions through immunohistochemical staining of muscles, including the splenius, triceps brachii, longissimus dorsi, and gluteus medius. The splenius and gluteus medius muscles, which exhibited the greatest differences in the proportion of slow-twitch fiber area, were selected for further comparison of differential metabolites and transcriptomic expression profiles between slow-twitch and fast-twitch fibers. A total of 27 energy metabolism-related differential metabolites, including pyruvate and lactate, were identified, along with 432 differentially expressed genes, such as PFKM and ALDOA. Additionally, 164 differentially expressed miRNAs, including miR-499 and miR-24-3p, were detected. We found highlighted differences in LDHA expression between the gluteus medius and splenius muscles, which may influence the conversion of fast and slow muscle fibers by modulating the glycolysis/gluconeogenesis pathway. The miRNA−mRNA targeting relationships established here warrant further validation. These findings provide valuable insights into the molecular mechanisms underlying energy metabolism differences in Yili horses.