Extraction system 811

The experimental diets and whole fish were analyzed following the AOAC protocols (2016) [15 ]. The moisture content of the samples was analyzed using the direct drying method. The samples were put in an oven at 105 ± 0.5 °C for 3 h until they reached a constant weight. The protein content of the whole fish was determined using automatic rapid nitrogen fixing (rapid N exceed, Elementar, Langenselbold, Germany). The ash content was determined by complete combustion of samples. Each sample (2.0 ± 0.5 g) was then ignited in the muffle furnace to ensure thorough combustion (600 °C, 2 h). The crude lipid content was determined using the Soxhlet extraction method with a Soxhlet extraction system (Extraction system-811, BUCHI, Flawil, Switzerland) and petroleum ether as the extraction solvent. The extraction process lasted for 10 h to ensure complete extraction of the lipid content from the sample. The gross energy content was determined through the utilization of a bomb calorimeter (LRY-600A, produced by Chuangxin Ltd., Hebei, China).

The experimental diets and fish were analyzed using an AOAC-based protocol (29 (link)). Moisture content was determined by drying the samples in an oven at 105°C until a constant weight was obtained. Crude protein (N × 6.25) was analyzed by measuring nitrogen using the Kjeldahl method (2300, FOSS, Sweden). Ash content was analyzed by carbonization at 300°C for 30 min, followed by incineration at 550°C for 4 h. Crude lipid was measured by the Soxhlet method (Extraction System-811, BUCHI, Switzerland).

The proximate composition of muscle was analyzed according to the standard methods (AOAC, 1995). Crude protein was determined by Kjeldahl method (2300, FOSS, Sweden) by measuring nitrogen (N × 6.25). Crude lipid was measured after diethyl ether extraction by Soxhlet method (Extraction System-811, BUCHI, Switzerland).
Glycogen content in muscle was determined using the commercial kit (Nanjing Jiancheng Bioengineering Institute, Nanjing, China) according to the manufacturer’s instructions. The absorbance was measured at 620 nm with a spectrophotometer (UV-2401PC, Shimadzu, Japan). Glycogen contents were expressed as mg per g of muscle (wet weight).