Disease is an enduring threat to aquaculture, with direct costs from outbreaks of more than US$6 billion a year. Efforts to reduce antibiotic use in aquaculture have resulted in a recent shift towards the use of immunostimulants that boost fish immune systems. Seaweeds are a potential source of unique immunostimulants because of their diverse taxonomy (11,353 species) and diverse bioactives, but there has been no synthesis of their effects on fish. A systematic review and meta‐analysis of 142 peer‐reviewed studies was conducted to evaluate the effects of seaweed on the innate immunity, resistance (to stress and pathogens) and growth of farmed fish. Overall, our review indicated that dietary supplementation with seaweeds or their extracts had substantial positive impacts on the health and growth of fish compared with control groups and were comparable to currently utilised immunostimulants. Dramatic effects on survival of fish during challenge experiments were detected, with an average of 33% higher survival of fish fed diets that included seaweeds or their extracts. This study provides broad evidence for the benefits of supplementing fish feed with the reviewed seaweeds or their bioactive extracts, including potential synergistic effects of supplements. However, the meta‐analysis also highlighted considerable variation among studies, and between fish and seaweed species, making it difficult to extrapolate results beyond individual experiments. Future studies should focus on developing synergistic combinations of ingredients and elucidating the mode of action through isolation of seaweed bioactives, together with standardisation of experimental conditions, to fast‐track the benefits of seaweed supplements for aquaculture.

中文翻译：

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对海藻及其提取物作为鱼类免疫刺激剂的荟萃分析：系统综述

疾病是对水产养殖业的持久威胁，每年因爆发而造成的直接损失超过60亿美元。减少水产养殖中抗生素使用的努力导致最近转向使用增强鱼类免疫系统的免疫刺激剂。海藻由于其不同的分类学（11,353种）和多种生物活性物质而成为潜在的独特免疫刺激剂的来源，但尚未合成其对鱼类的作用。对142项同行评审的研究进行了系统的综述和荟萃分析，以评估海藻对养殖鱼类的先天免疫，抵抗力（对压力和病原体）的抵抗力和生长的影响。全面的，我们的评论表明，与对照组相比，膳食补充海藻或其提取物对鱼类的健康和生长具有重大的积极影响，并且与目前使用的免疫刺激剂相当。在挑战实验期间，对鱼类存活率产生了显着影响，其中以海藻或其提取物为食的鱼类饲喂日粮的存活率平均提高了33％。这项研究提供了广泛的证据，证明用审查过的海藻或其生物活性提取物补充鱼饲料的好处，包括补充剂的潜在协同作用。但是，荟萃分析还强调了研究之间以及鱼类和海藻物种之间的巨大差异，因此很难将结果推论到单个实验之外。