Table_1_The comparison of largemouth bass (Micropterus salmoides) fed trash fish and formula feeds: Growth, flesh quality and metabolomics.DOCX

This study compared the growth, flesh quality and metabolomics of largemouth bass (Micropterus salmoides) fed trash fish and formula feeds. Trash fish (TF), self-made feed (SF) and commercial feed (CF) were prepared with crude protein levels of 172.2 g/kg, 503.5 g/kg and 504.1 g/kg (666.2 g/kg, 547.3 g/kg and 535.1 g/kg based on dry matter), respectively. Then, the three diets were fed to largemouth bass with an initial body weight of 75.0 ± 0.1 g for 12 weeks. SF and CF groups presented significantly lower feed intake (FI), feed conversion ratio (FCR) and higher protein efficiency ratio (PER) than TF group based on dry matter basis without affecting the weight gain (P < 0.05). The yellowness (b*) in dorsal muscle, flesh heat-insoluble collagen and free flavor amino acids contents in SF group were significantly higher (P < 0.05), while drip loss were significantly lower (P < 0.05) than those of TF group. Compared to TF group, SF and CF groups showed significantly higher flesh polyunsaturated fatty acids (PUFAs), n-3 PUFAs and n-6 PUFAs contents, flesh hardness, shear force and muscle fiber density (P < 0.05), and lower flesh total free amino acids, essential amino acids, muscle fiber diameter, intestine villus height and muscular thickness (P < 0.05). The serum total protein, triglyceride and cholesterol levels in SF group were significantly lower than those in TF and CF groups (P < 0.05). In the muscle metabolomics, 177 differential metabolites were detected between SF and TF groups, which mainly enriched in pathways as biosynthesis of amino acid, histidine metabolism, glycine, serine and threonine metabolism, etc. Conclusively, feeding largemouth bass with formula feeds improved flesh fatty acid profile and flesh texture without negative effects on the growth, but the flesh free amino acids contents were lower than the fish fed trash fish.

本研究比较了投喂冰鲜杂鱼（trash fish, TF）、自制配合饲料（self-made feed, SF）与商品配合饲料（commercial feed, CF）的大口黑鲈（*Micropterus salmoides*）的生长性能、肉质品质及代谢组学特征。三种试验饲料的粗蛋白水平分别为172.2 g/kg、503.5 g/kg和504.1 g/kg（以干物质计则分别为666.2 g/kg、547.3 g/kg和535.1 g/kg）。选取初始体重为75.0 ± 0.1 g的大口黑鲈作为实验对象，分别投喂上述三种饲料，养殖周期为12周。以干物质为基准进行统计分析，SF组与CF组的摄食量（feed intake, FI）、饲料系数（feed conversion ratio, FCR）均显著低于TF组，而蛋白质效率比（protein efficiency ratio, PER）显著高于TF组，且两组对实验鱼的增重率无显著影响（P < 0.05）。与TF组相比，SF组大口黑鲈背部肌肉的黄度值（b*）、肌肉热不溶性胶原蛋白含量及游离风味氨基酸含量均显著升高（P < 0.05），而肌肉滴水损失显著降低（P < 0.05）。相较于TF组，SF组与CF组的实验鱼肌肉多不饱和脂肪酸（polyunsaturated fatty acids, PUFAs）、n-3多不饱和脂肪酸及n-6多不饱和脂肪酸含量、肌肉硬度、剪切力及肌纤维密度均显著升高（P < 0.05）；同时，两组实验鱼的肌肉总游离氨基酸、必需氨基酸含量、肌纤维直径、肠道绒毛高度及肠壁肌层厚度均显著降低（P < 0.05）。SF组实验鱼的血清总蛋白、甘油三酯及胆固醇水平均显著低于TF组与CF组（P < 0.05）。肌肉代谢组学分析结果显示，SF组与TF组共检测到177个差异代谢物，这些差异代谢物主要富集于氨基酸生物合成、组氨酸代谢、甘氨酸-丝氨酸-苏氨酸代谢等通路。综上，投喂配合饲料可改善大口黑鲈的肌肉脂肪酸组成与质地，且对其生长性能无负面影响，但实验鱼的肌肉游离氨基酸含量低于投喂冰鲜杂鱼的对照组。