With their enormous muscle mass and athletic ability, horses are well-positioned as model organisms for understanding muscle metabolism. The main objective of this study was to evaluate the breed-specific mechanisms controlling muscle metabolism. As expected, the glycogen content, citrate synthase, and hexokinase activity of muscle were significantly higher in GZ horses. To alleviate the false positive rate, we used both MS1 and MS2 ions for metabolite classification and differential analysis.
As a result, a total of 51, MS1 and MS2 metabolites were identified, and these metabolites can separate these two groups from each other. Seven of the 13 metabolites were also found in thoroughbred racing horses, suggesting that metabolites related to antioxidants, amino acids, and lipids played a key role in the development of skeleton muscle in horses. Those metabolites related to muscle development shed a light on racing horses' routine maintenance and improvement of athletic performance.
The excellent locomotion and racing performance of horses depend on their skeletal muscle metabolism. Therefore, the horse is a supremely effective animal model for understanding the effects of metabolism on muscle development 1. However, metabolite regulation mechanism associated with the training or development of horses remains unclear 2 , 3. Previous studies have focused on diseases-related and exercise-related metabolites, for instance, the hematometabolic characteristics of blood metabolism in horses with atypical myopathy AM 4 and the identification of the biomarkers for acute laminitis by serum 5 metabolomics, and provide indexes for clinical diagnosis.
Furthermore, the metabolomics of blood 6 , 7 and muscle 8 for horses during endurance exercise reasons out the energetic demands for locomotion. Undoubtedly, metabolomics analysis has practical use for tracking stimulants from equine urine 9 β 11 , and the analysis can also reflect exercise fatigue 12 , 13 during exercise and training.
Nevertheless, its utility is being increasingly acknowledged between different species [e. Moreover, metabolomics has been applied to other livestock studies 19 β Thus, metabolomics can afford opportunities to understand metabolic mechanisms between different breeds.
