2.6.1. Sample Preparation and Extraction

Six samples from each group (FG and SG; 10 individuals mixed in one sample) were prepared for widely targeted metabolomic analysis. The procedures were performed as previously described [14]. Briefly, the meat samples were homogenized with steel balls (30 Hz) for 20 s, and centrifuged (650× g, 4 °C) for 30 s. The powder was mixed with 400  μL of 70% methanol–water (internal standard extractant chromatographically pure, BioBioPha/Sigma-Aldrich, St. Louis, MO, USA), oscillated (162× g) for 5 min, and centrifuged at 10,390× g for 10 min at 4°C. Finally, 300 μL of supernatant was collected and stored at −20 °C for 30 min, and then centrifuged at 10,390× g at 4 °C for 3 min. The supernatant was used for further analyses.