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

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.

Our hypothesis is that nutritional programming can improve and enhance the capability of Atlantic salmon to effectively and efficiently utilise sustainable feeds formulated with very low levels of marine ingredients. The nutritional programming concept involves exposing an animal to a dietary stimulus early in life that alters that individual metabolically and physiologically such that it becomes adapted and better able to respond to a similar nutritional challenge later in life. This concept was first studied and demonstrated in rodents and subsequently applied to both human and agricultural livestock animals and, more recently, was demonstrated to be applicable in some fish species. Recently, we showed that an early nutritional intervention in Atlantic salmon at first feeding using a diet formulated almost entirely with plant proteins and oils, with only a very low level of fishmeal and no fish oil, resulted in fish better adapted to utilise this feed later in life. Thus, when challenged with this diet 3 months later, the fish showed improved growth performance despite having similar feed intake, which was reflected in higher feed efficiency and increased nutrient retention. Specifically, the retentions of the key omega-3 fatty acids, EPA and DHA, were greatly increased in fish subjected to the nutritional programming. The overall aim of the present project is to determine the optimal feeding regime to enable nutritional programming in salmon and to assess the long-term effects (18 months) of a short (~1 week) nutritional intervention at first feeding on Atlantic salmon. Growth, feed efficiency and nutritional quality will be assessed and the underlying molecular mechanisms of both metabolism and immune function will provide insights to the processes underpinning the response to initial diet, and to assess the potential for commercial application.

Outcomes from this research will impact at many levels, including academia, the salmon feed and production industry, consumers and the general public. Primary exploitation will be through development and production of new feed formulations designed to "programme" fish to better utilise sustainable feeds with high levels of replacement of dwindling and expensive marine ingredients, fishmeal and fish oil, currently used in UK aquafeeds. The project will therefore provide industry with strategies with potential to improve the economic viability and sustainability of UK aquaculture. Tangible outcomes will therefore be more effective use of sustainable feeds formulated with low marine ingredients with reduced negative impacts on flesh n-3 LC-PUFA levels in farmed salmon, expandable to all sectors of the aquaculture industry. However, our exploitation strategy will be far wider than just the feed manufacture sector, as we will target the fish production industries as a whole, and increase awareness of the potential of nutritional programming to mitigate fish health and product quality issues associated with sustainable feeds.
There are two main industrial beneficiaries, the UK salmonid farming, and aquaculture feed industries. The aquafeed industry itself will play a key central role in the commercial application and uptake of the feed formulation and feeding strategies to be developed and evaluated, with project partner BioMar taking a lead role. The Universities of Stirling (UoS) and Aberdeen (UoA) have both worked extensively with BioMar for more than a decade, collaborating on several research studies including recent BBSRC IPA and BBSRC-NERC projects, and PhD CASE studentships. Moreover, both UoS and UoA have long and established histories as centres of excellence for fish nutrition and health research and are recognised as trusted sources of independent research. However, UoS and UoA have extensive links with all sectors and key stakeholders in the UK aquaculture industry that involve regular direct contact, engagement and discussion. Thus, we will use these well-established links including the industry-led Scottish Aquaculture Innovation Centre (SAIC), to engage with potential end-users including major fish farming companies, to ensure industry-wide dissemination and engagement. Currently, UoS and UoA have many joint projects and PhD studentships with industrial partners at all levels of the industry and these direct personal links are ideal for a two-way flow of information, and actively involving and engaging end users, stakeholders and beneficiaries, seeking their input throughout the project. UoS and UoA membership of MASTS (Marine Alliance for Science and Technology Scotland) ensures that the research and inter-disciplinary collaborations it involves strengthen basic and strategic aspects of marine science in the UK. Since MASTS involves both Government and HEIs, knowledge will be rapidly disseminated to relevant stakeholders and used to develop further collaborations and strategic initiatives in this key area of research. Communication of issues relating to human health, such as farmed fish and dietary omega-3 will be effected through our existing contacts directly in Government (e.g. Food Standards Agency, and the Scottish Executive), and through various currently-developing pan-Governmental food security initiatives that we are involved with. Project results will not only be published as usual in scientific peer-reviewed literature (conference proceedings and papers in high impact journals), but also disseminated widely to industry through contributions to trade and professional magazine articles and online sites such as FISHupdate, and the public via Institutional web pages, and social media as well as mainstream media articles in local and national press and interviews.