Shrimp consumption has increased steadily around the world, as has the emergence of bacterial pathogens, which cause massive economic losses. The incorporation of plant extracts in aquatic animal feeds has been suggested to improve growth performance and resistance against bacterial pathogens. Therefore, the aim of this study was to evaluate the effects of Cajeput Melaleuca cajuputi leaf extract (MCLE) on the growth performance, physiological responses and resistance of Giant freshwater prawn Macrobrachium rosenbergii against Aeromonas hydrophila. The phytochemical composition of the MCLE was analysed using gas chromatography–mass spectrometry (GC-MS). Thereafter, the MCLE was included in diets (0.0, 5.0, 10.0 and 15.0 g/kg) fed to the M. rosenbergii. The growth was observed after 45 days of the feeding trial, whereas physiological responses and clearance efficiency (%) against A. hydrophila were observed on the 60th day. 2-Isopropyl-10-methylphenanthrene, phenanthrene, 1-methyl-7-(1-methyl ethyl) and 4H-1-Benzopyran-4-one, 3-acetyl-5, 7-dihydroxy-2-methyl- compounds were detected as the major compounds in the MCLE. A significant improvement (p < 0.05) of growth and survival of M. rosenbergii fed with MCLE supplementation at 15.0 g/kg was observed. The total haemocyte count, hyaline cells and granular cells were also increased (p < 0.05) in the M. rosenbergii fed with diets included with MCLE. Upon challenging the primed M. rosenbergii with sub-lethal doses of A. hydrophila, the highest clearance efficiency (73%) was achieved in the prawn-fed 15.0 g/kg MCLE based diet (p < 0.05) after 96 h post injection. These findings indicate the potential of MCLE supplementation to improve growth, immune responses of M. rosenbergii and their resistance against A. hydrophila.

中文翻译：

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罗氏沼虾日粮中添加 Cajeput Melaleuca cajuputi 提取物：对嗜水气单胞菌生长、免疫反应和抗性的见解

世界各地的虾消费量稳步增长，细菌病原体的出现也是如此，这造成了巨大的经济损失。有人建议在水产动物饲料中加入植物提取物以提高生长性能和对细菌病原体的抵抗力。因此，本研究的目的是评估Cajeput Melaleuca cajuputi叶提取物（MCLE）对罗氏沼虾生长性能、生理反应和抗嗜水气单胞菌抗性的影响。使用气相色谱-质谱 (GC-MS) 分析 MCLE 的植物化学成分。此后，MCLE 被纳入饲喂M的日粮（0.0、5.0、10.0 和 15.0 g/kg）. 罗氏沼虾_ 在饲养试验 45 天后观察到生长，而对A 的生理反应和清除效率 (%) 。 第60天观察到嗜水菌。检测到2-异丙基-10-甲基菲、菲、1-甲基-7-(1-甲基乙基)和4H-1-苯并吡喃-4-酮、3-乙酰基-5、7-二羟基-2-甲基-化合物作为 MCLE 中的主要化合物。M 的生长和存活显着改善 ( p < 0.05) 。 观察到以 15.0 g/kg 补充 MCLE 的罗氏沼虾。M中的总血细胞计数、透明细胞和颗粒细胞也增加（p  < 0.05）。 罗氏沼虾饲喂包含 MCLE 的日粮。在挑战已启动的M时。与亚致死剂量的A.hydrophila罗氏沼虾相比，在 15.0 g/kg MCLE 对虾饲喂 96 小时后，其清除效率最高（73%）（ p < 0.05）。这些发现表明补充 MCLE 有可能改善M的生长和免疫反应。 罗氏沼虾及其对A的抗性。 嗜水菌