Abstract This study evaluated the effects of SOD-rich melon pulp concentrate (MPC) premix on growth performance, hematological profile and the antioxidant capacity of Nile tilapia (Oreochromis niloticus) subjected to heat/dissolved oxygen-induced stress (HDOIS). A group of 462 male Nile tilapia (8.87 ± 0.12 g) was randomly distributed in 42,250-L tank (11 fish/tank) and fed seven practical diets supplemented with graded levels of MPC (0.0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5% and 1.0% MPC premix of diet; PM Melofeed 2.5, SOD activity min. 65,000 IU kg−1, Lallemand SAS, Blagnac, France) with six replicate tank/diet. The diets were formulated to contain 30% crude protein and 18 MJ kg−1 crude energy. After 60 days of feeding, growth performance was evaluated and six fish per treatment were sampled for hematological profile and analysis of the hepatic activity of key antioxidant enzymes. Then, remaining fish were subjected to HDOIS (34 °C/1.87 mg L−1 dissolved oxygen) for 2 days and the same hematological profile and antioxidant enzyme activities were determined. MPC supplementation was associated with the recruitment of hepatic antioxidant defense in the form of increased SOD activity prior and after HDOIS as well as of GR activity before HDOIS at 0.4% MPC and above. These levels of MPC supplementation were weakly associated with reduced level of muscle lipid oxidation. This trial indicates that MPC supplementation at or above 0.4% contributes to a better maintenance of antioxidant defense in Nile tilapia when exposed to HDOIS environmental stress. This is expected to yield biological benefits in the longer-term when Nile tilapia are chronically or repetitively exposed to similar environmental stressors as may be the case under intensive aquaculture conditions.

中文翻译：

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富含 SOD 的甜瓜果肉浓缩物对尼罗罗非鱼（Oreochromis niloticus）在热/溶氧胁迫下生长性能和抗氧化状态的推定影响

摘要 本研究评估了富含 SOD 的甜瓜果肉浓缩物 (MPC) 预混物对尼罗罗非鱼 (Oreochromis niloticus) 受到热/溶解氧诱导应激 (HDOIS) 的生长性能、血液学特征和抗氧化能力的影响。一组 462 条雄性尼罗罗非鱼 (8.87 ± 0.12 g) 随机分布在 42,250 升的鱼缸中（11 条鱼/鱼缸），并饲喂七种添加了分级水平 MPC（0.0%、0.1%、0.2%、0.3%）的实用日粮、0.4%、0.5% 和 1.0% MPC 预混料；PM Melofeed 2.5，SOD 活性最低 65,000 IU kg-1，Lallemand SAS，Blagnac，法国），具有六个重复的罐/日粮。日粮配制成含有 30% 的粗蛋白和 18 MJ kg-1 的粗能量。经过60天的喂养，对鱼的生长性能进行了评估，每种处理对 6 条鱼进行了血液学分析和关键抗氧化酶的肝脏活性分析。然后，剩余的鱼接受 HDOIS（34 °C/1.87 mg L-1 溶解氧）2 天，并测定相同的血液学特征和抗氧化酶活性。MPC 补充剂与肝脏抗氧化防御的募集有关，表现为 HDOIS 前后 SOD 活性增加，以及 HDOIS 前 0.4% MPC 及以上的 GR 活性增加。这些 MPC 补充水平与肌肉脂质氧化水平的降低有微弱的相关性。该试验表明，当尼罗罗非鱼暴露于 HDOIS 环境压力时，添加 0.4% 或以上的 MPC 有助于更好地维持尼罗罗非鱼的抗氧化防御。