The current study aimed to evaluate growth performance, digestive enzyme activities, antioxidant status, nonspecific immune response and intestinal histological status of red tilapia fed Daphnia meal (DM) as a substitute for fishmeal (FM). Hybrid red tilapia (Oreochromis mossambicus × Oreochromis aureus) fry (0.54 ± 0.05 g fish⁻¹) was allocated in nylon haba cages (100 fry m⁻³) for 2 weeks as an acclimation period. The fish were divided into five groups (three replicates each). The experimental diets were prepared by replacing FM with DM at concentrations of 25%, 50%, 75% and 100% respectively. The results indicated that fish fed increasing levels of DM (50%–75%) experienced high growth performance, feed utilisation and protein content. The activities of digestive enzymes were significantly increased in all groups fed DM diets compared to the control. The antioxidant balance was improved by decreasing the level of malondialdehyde and increased the total antioxidant capacity, catalase, superoxide dismutase and glutathione reductase activities in the liver of fish fed DM. The nonspecific immune response, including lysozyme, alkaline phosphatase activities and total protein level improved significantly with increasing FM substitution levels by DM in a dose-dependent manner. Histometric analysis of the intestinal wall revealed an increase in the villus length, crypts depth and goblet cells number in groups fed DM meal up to 50% substitution level compared to other treatments. It may be concluded from results of this feeding trial that in the aquaculture of hybrid tilapia, FM may be substituted with up to 50% DM without compromising intestinal health, growth performance and immune status of the fish.

中文翻译：

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在杂交红罗非鱼日粮中使用水蚤粉替代鱼粉会影响生长性能、消化酶活性、抗氧化剂、免疫状态和肠道组织学参数

本研究旨在评估以水蚤粉（DM）替代鱼粉（FM）喂养的红罗非鱼的生长性能、消化酶活性、抗氧化状态、非特异性免疫反应和肠道组织学状态。将杂交红罗非鱼（Oreochromis mossambicus  ×  Oreochromis aureus）鱼苗（0.54 ± 0.05 g 鱼^-1）分配到尼龙哈巴网箱（100 鱼苗 m ^-3）中，进行 2 周的驯化期。将鱼分为五组（每组三个重复）。实验日粮是用DM代替FM，浓度分别为25%、50%、75%和100%。结果表明，饲喂增加 DM 水平（50%–75%）的鱼具有较高的生长性能、饲料利用率和蛋白质含量。与对照组相比，所有喂食 DM 饮食的组的消化酶活性均显着增加。通过降低丙二醛水平来改善抗氧化平衡，并提高饲喂DM的鱼肝脏中的总抗氧化能力、过氧化氢酶、超氧化物歧化酶和谷胱甘肽还原酶活性。随着DM以剂量依赖性方式增加FM替代水平，非特异性免疫反应，包括溶菌酶、碱性磷酸酶活性和总蛋白水平显着改善。肠壁的组织计量分析显示，与其他处理相比，饲喂 DM 餐的组的绒毛长度、隐窝深度和杯状细胞数量增加至 50% 替代水平。从本次饲养试验的结果可以得出结论，在杂交罗非鱼的养殖中，FM可以用高达50%的DM替代，而不会影响鱼的肠道健康、生长性能和免疫状态。