Investigating the potential of nutritional programming to improve the utilisation of sustainable feeds in aquaculture

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This project will use the concept of "nutritional programming" to improve the efficiency of feed utilisation in aquaculture. Nutritional programming involves an early dietary intervention that can stimulate physiological functions during sensitive, early developmental stages, and effectively "programme" metabolic and immunological processes so that the animal can respond better to a similar dietary challenge later in life. Specifically the project will address issues with current salmon diets that now use high levels of plant protein and oils, which can lead to reduced performance in the fish and the final product that has lower levels of omega-3 fatty acids. Fish are an important component of a healthy diet providing high quality protein, key minerals and vitamins, and an almost unique source of the essential omega-3 fatty acids, EPA and DHA. Increased dietary intake of these omega-3 fatty acids is associated with beneficial health effects, including reducing incidence and severity of inflammatory and pathological conditions including cardiovascular, neurological and developmental diseases. However, all marine fisheries are fully exploited and, since 2015, more than half of all fish and seafood is now supplied by aquaculture. Paradoxically, farmed fish, such as salmon, are themselves reliant on finite and limited supplies of fishmeal (FM) and fish oil (FO), themselves derived from marine fisheries. Alternative, more sustainable feeds have been developed with much of the FM and FO replaced by plant proteins and oils. While the replacement strategy has been in the most part successful it has had a major consequence in reducing levels of EPA and DHA in farmed fish compromising their nutritional quality for consumers. The level of replacement has now reached a critical point where it is having potentially detrimental effects on fish growth, feed efficiency and, importantly, fish health. The key aim of the present research is to develop new cutting-edge feeding strategies to improve the utilisation of sustainable feeds based on plant ingredients and thereby enhance the efficient production of healthy and nutritious farmed fish to benefit UK aquaculture and human consumers. The nutritional programming concept has been investigated in mammals and gained interest in human health studies. Results indicated that controlled early nutrition can improve growth and development, and reduce incidence or severity of particular health issues. In agriculture, understanding the consequential importance of the impact of early nutrition may help to improve production and mitigate potential problems of new feeds. Previously, we showed that a brief exposure of salmon at first feeding to a diet with very low marine ingredients improved the growth of the fish when they were challenged 3-months later with a similar low marine diet. This effect was not related to feed intake but to improved nutrient utilisation and retention and, specifically, EPA and DHA retention were increased many-fold. The over arching objective of the present study is to determine the potential of nutritional programming to improve the efficiency of sustainable feeds with very low marine (low omega-3) ingredients in long-term studies from first-feeding through to market size with focus on defining not only the molecular and genetic mechanisms involved in nutritional programming but also the effects on fish health quantifying the potential commercial benefits of applying this strategy 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 utilisation of modern alternative feeds in aquaculture, enhancing production and feed efficiency, while maintaining the health and nutritional quality of farmed fish, delivering greater sustainability and food security.