The formulator of aquatic diets is part of a continuous search for alternative protein sources instead of depreciated fish meal. The utilization of zooplankton as a feed ingredient is an interesting trend due to their high-quality protein content and abundance of essential nutrients. The current study aims to investigate the effects of partial and total replacement of fish meal (FM) by Dahpnia magna meal (DMM) on growth performance, feed utilization, histological, and economic status of mullet, M. cephalus, larvae. In addition to the control diet, 100% FM, D₀, four diets containing DMM at different levels were used: 25% (D₂₅), 50% (D₅₀), 75% (D₇₅), and 100% (D₁₀₀) replacement of fish meal. A total of 300 larvae (0.097 ± 0.001 g) were equally divided into five groups (three replicate per each group) at a density of 200 larvae m⁻³. The aquariums were renewed at a rate of 30% daily. During the 60-day experimental period, all larvae were fed their respective diets at a level of 20% of live body weight, five times a day (9.00 a.m., 12.00, 15.00, 18.00, and 21.00 p.m.). The results indicated that compared to D₀, fish fed D₇₅ recorded the highest significant value of growth, and feed utilization parameters, while fish fed D₁₀₀ achieved the lowest feed cost and incidence cost, and the highest profit index and economic efficiency ratio. A strong correlation was reported among weight gain, feed conversion ratio and fish meal replacement with DMM; R² = 0.94 and 0.91, respectively. The fit regression model representing mullet response to FM replacement with DMM is a poly-nominal regression model with maximum response at 75–100%. The histological investigation of the intestine revealed an improvement of histomorphometric indices and goblet cell number with increasing DMM inclusion levels. These findings confirmed that 75% to 100% partial substitution of FM with DMM is the ideal replacement for mullet, M. cephalus, larvae for improving fish growth performance and feed utilization.

中文翻译：

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新饲料 Daphnia magna (Straus, 1820) 作为鱼粉替代品对灰鲻鱼、Mugil cephalus (Linnaeus 1758) 的生长、饲料利用、组织学状态和经济收入的影响

水产饲料的配方师是不断寻找替代蛋白质来源而不是贬值的鱼粉的一部分。由于浮游动物的高质量蛋白质含量和丰富的必需营养素，将浮游动物用作饲料成分是一个有趣的趋势。目前的研究旨在调查用大溞粉 (DMM)部分和全部替代鱼粉 (FM)对鲻鱼、M. cephalus、幼虫的生长性能、饲料利用、组织学和经济状况的影响。除了对照饮食、100% FM、D _{0 之外}，还使用了四种含有不同水平 DMM 的饮食：25% (D ₂₅ )、50% (D ₅₀ )、75% (D ₇₅ ) 和 100% (D ₁₀₀) 替代鱼粉。将总共​​ 300 只幼虫 (0.097 ± 0.001 g) 以 200 只幼虫 m ^-3的密度平均分为五组（每组三个重复）。水族馆每天更新30%。在 60 天的实验期间，所有幼虫都以活体重的 20% 的水平喂食各自的饮食，每天五次（上午 9 点、12 点、15 点、18 点和 21 点）。结果表明，与 D ₀相比，饲喂 D _{75 的}鱼记录了最高的生长和饲料利用参数的显着值，而饲喂 D _{100 的}鱼实现了最低的饲料成本和发病成本，最高的利润指标和经济效益比。据报道，体重增加、饲料转化率和用 DMM 替代鱼粉之间有很强的相关性；R ²分别为 0.94 和 0.91。表示用 DMM 替换 FM 的鲻鱼响应的拟合回归模型是多项式回归模型，最大响应为 75-100%。肠道的组织学研究表明，随着 DMM 包含水平的增加，组织形态学指标和杯状细胞数量有所改善。这些发现证实，用 DMM 75% 到 100% 部分替代 FM 是用于改善鱼类生长性能和饲料利用率的鲻鱼、M. cephalus、幼体的理想替代品。