The present study was conducted to evaluate the utilization of both pelleted feed (PF) and extruded feed (EF) by blunt snout bream Megalobrama amblycephala based on growth performance, stress responses, innate immunity and disease resistance. Both the PF and EF were prepared with the same formula. Fish were divided randomly into 2 groups, including one fed the PF continuously and one offered the EF continuously. The whole feeding trial lasted 8 weeks, after which fish were subjected to Aeromonas hydrophila infection. The results showed that the feed intake, feed conversion ratio, hepatic total superoxide dismutase activity and glutathione content, plasma complement 3 and complement 4 levels as well as myeloperoxidase activity of the EF group were all significantly lower than those of the PF group, while the opposite was true for the condition factor, the viscera index, the abdominal fat percentage, nitrogen and energy retention, hepatic malondialdehyde content, plasma levels of cortisol, glucose, lactate, total protein and globulin as well as the activities of plasma alanine aminotransferase and aspartate aminotransferase. In addition, the EF group also obtained relatively low activities of hepatic glutathione peroxidase and plasma acid phosphatase as well as high cumulative mortality rates at 24–96 h after Aeromonas hydrophila challenge. Furthermore, the feed cost of culturing this species with EF is lower than that with PF. These findings indicated that compared with PF, EF could increase the feed utilization and economic benefits of blunt snout bream, but reduce its anti-stress ability, non-specific immunity, A. hydrophila resistance and feed cost.

中文翻译：

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钝头鲷 Megalobrama amblycephala 对颗粒和挤压饲料的利用：从生长性能、健康状况和饲料成本方面的见解

本研究旨在根据生长性能、应激反应、先天免疫和抗病性评估钝头鲷Megalobrama amblycephala对颗粒饲料 (PF) 和膨化饲料 (EF) 的利用。PF 和 EF 均采用相同的配方制备。将鱼随机分为两组，一组连续投喂PF，一组连续投喂EF。整个饲喂试验持续了 8 周，之后对鱼进行嗜水气单胞菌感染。结果表明，EF组采食量、饲料转化率、肝脏总超氧化物歧化酶活性和谷胱甘肽含量、血浆补体3和补体4水平以及髓过氧化物酶活性均显着低于PF组，而病情因素、内脏指数、腹部脂肪百分比、氮和能量潴留、肝脏丙二醛含量、皮质醇、葡萄糖、乳酸、总蛋白和球蛋白的血浆水平以及血浆丙氨酸氨基转移酶和天冬氨酸的活性则相反氨基转移酶。此外，EF组肝谷胱甘肽过氧化物酶和血浆酸性磷酸酶活性较低，术后24～96 h累积死亡率较高。嗜水气单胞菌挑战。此外，用 EF 培养该物种的饲料成本低于用 PF 培养的饲料成本。这些研究结果表明，与PF相比，EF可以提高鲷鱼的饲料利用率和经济效益，但会降低其抗应激能力、非特异性免疫能力、A . 亲水性抗性和饲料成本。