Novel Omega-3 Sources in Feeds and Impacts on Salmon Health

饮食中的欧米伽-3脂肪酸是对健康有益的关键营养素，在免疫系统中起着关键作用，同时有助于心脏的正常功能和大脑的发育。人体不能产生omega-3，这就是为什么吃这些必需脂肪很重要的原因。鱼类和海产品是人类饮食中omega-3的独特来源，但传统渔业的衰落意味着现在消费的鱼类中有一半以上是人工养殖的。直到最近，确保养殖鱼类和海产品中高含量的omega-3的唯一方法是通过使用海洋原料、鱼粉和鱼油在饲料中提供这些营养素。然而，矛盾的是，它们也来自处于可持续极限的海洋渔业，使它们成为有限的资源。在过去的二十年里，养鱼业的迅速扩张是由于越来越多的传统海洋原料被更经济的替代品稀释，主要是植物膳食和植物油，它们缺乏鱼类中发现的-3脂肪酸。因此，近年来，大西洋鲑鱼养殖中这些替代饲料的发展使养殖鲑鱼中omega-3的含量减少了一半。饮食中的欧米伽-3对鱼的健康同样重要，就像对人类一样。与养殖鱼类的生产性能和健康有关的一些负面问题与替代的低含量海洋饲料的发展并行，这些饲料有益的omega-3含量较低，包括炎症性疾病的发病率和严重程度较高。然而，此外，炎症是对所有病原体（包括寄生虫、细菌和病毒感染）的免疫反应的关键组成部分，因此目前养殖鱼类饲料中低水平的omega-3已经对鱼类的健康和福利产生了影响。因此，饮食中omega-3含量的降低对鱼类健康的双重影响，以及为人类消费者提供的养殖鱼类产品的营养质量，意味着鱼类养殖，特别是鲑鱼养殖，已经率先努力突出和缩小关键omega-3营养素的供需差距。具体来说，全球鲑鱼倡议组织宣布了一项招标，要求商业组织每年提供多达20万吨富含ω -3的新型油。此外，包括世界银行在内的一个财团宣布了F3（无鱼饲料）鱼油挑战，以创造一种无鱼的“鱼油”替代品。因此，从海洋微藻和转基因油籽作物中提取富含欧米茄-3脂肪酸的新来源已被开发出来，并作为养殖鱼类（包括鲑鱼）的饲料原料进行了测试。虽然这些研究已经证明了这些新油在增加养殖鱼类的omega-3含量方面的有效性，但对鱼类健康的影响却被忽视了。该项目将直接调查全新的富含omega-3的油作为养殖大西洋鲑鱼的饲料成分对健康的重要影响。这些研究不仅将集中于确定新的omega-3来源对鲑鱼对特定疾病和寄生虫挑战的反应的影响，而且还将确定支撑鱼类健康的生化和分子机制，量化这些新的膳食油在英国鲑鱼养殖中的应用潜力。该建议是及时的、高度相关的和适当的，因为它响应了当前的需求，通过前沿研究来提高现代鱼类养殖替代饲料的质量和有效性，提高产量和饲料效率，同时保持养殖鱼类的健康和改善营养质量，提供更大的可持续性和粮食安全。

Dietary omega-3 fatty acids are key nutrients that have beneficial health effects playing a critical role in the immune system as well as contributing to the normal function of the heart and development of the brain. The human body is unable to produce omega-3, which is why it is important to eat these essential fats. Fish and seafood are unique sources of omega-3 in the human diet, but decline in traditional fisheries means that more than half of all fish consumed is now farmed. Until recently the only way to ensure high levels of omega-3 in farmed fish and seafood was to deliver these nutrients in feeds by using the marine ingredients, fishmeal and fish oil. However, paradoxically, they too are derived from marine fisheries that are at their sustainable limit making them finite and limited resources. The rapid expansion of fish farming in the last two decades has ony been possible with increasing dilution of the traditional marine ingredients with more economical alternatives, primarily plant meals and vegetable oils that lack the omega-3 fatty acids found in fish. Therefore, the development of these alternative feeds in Atlantic salmon (Salmo salar) farming has seen levels of omega-3 in farmed salmon halved in recent years. Dietary omega-3 are equally essential for the health of fish, just as they are for humans. Several negative issues related to farmed fish performance and health have paralleled the development of alternative, low marine feeds with reduced levels of the beneficial omega-3, including higher incidence and severity of inflammatory diseases. However, in addition, inflammation is a key component of the immune response to all pathogens, including parasitic, bacterial and viral infections and so the current low levels of omega-3 in feeds for farmed fish has had consequences for fish health and welfare. Thus, the dual impacts of reduced dietary omega-3 levels on fish health, and the nutritional quality of farmed fish products for human consumers has meant that fish farming, especially of salmon, has spearheaded efforts to both highlight and close the gap between supply and demand for the key omega-3 nutrients. Specifically, the Global Salmon Initiative announced a tender for commercial organisations to supply up to 200,000 tons annually of novel omega-3-rich oils. In addition, a consortium including The World Bank, announced the F3 (Fish Free Feed) Fish Oil Challenge to create a fish-free 'fish oil' substitute. Consequently, new sources of omega-3-rich oils from marine microalgae and genetically-modified oilseed crops have been developed and tested as feed ingredients for farmed fish, including salmon. While these studies have proved the effectiveness of these new oils in increasing omega-3 content of farmed fish, the impact on fish health has been neglected. This project will directly investigate the important health impacts of entirely novel omega-3 rich oils as feed ingredients for farmed Atlantic salmon. The studies will focus on determining not only impact of the new omega-3 sources on the response of salmon to specific disease and parasite challenges, but also on defining the biochemical and molecular mechanisms underpinning fish health, quantifying the potential of these new dietary oils for use in UK salmon farming. The proposal is timely and highly relevant and appropriate as it responds to current needs with cutting edge research to improve the quality and effectiveness of modern alternative feeds in fish farming, enhancing production and feed efficiency, while maintaining the health and improving the nutritional quality of farmed fish, delivering greater sustainability and food security.