Effect of vegetarian feeds on farmed fish
In Europe, most farmed species of fish are carnivorous; their feed contains fish meal (FM) and fish oil (FO) derived from wild stocks caught at sea. However, demand for this ‘raw material’ is now increasing from the expanding aquaculture sector and the human health sector that uses FO in food supplements. There is a growing need for sustainable alternative ingredients, such as plant-based feeds to reduce pressure on marine resources. Biologists from the ARRAINA (Advanced research initiatives for nutrition and aquaculture) project investigated the nutrient requirements of the five most commonly farmed fish species in Europe: Atlantic salmon, Rainbow trout, European seabass, Gilthead seabream and Common carp. This information was used to develop sustainable plant-based aquaculture feeds tailored to the requirements of each species, but containing lower levels of FM and FO. ‘The aim was to provide flexibility in the use of cost-efficient and environmentally friendly ingredients in the formulation of feeds in order to produce seafood of high nutritional value and quality’, explains Dr Sadasivam Kaushik, the coordinator of ARRAINA. He adds, ‘Beneficiaries will include all those linked with the European fish farming sector, from suppliers of feedstuffs to feed producers and farmers.’ Biomarkers measure effects Project partners developed tools based on relevant biomarkers to measure and predict the effects of alternative feeds on fish metabolism and to identify the nutritional requirements for each species over the whole life cycle. Researchers measured the long-term effects of changes in dietary formulations on fish performance, including threshold effects, nutritional intervention in early life stages and the impact of maternal diet on larvae. According to Dr Kaushik, ‘Developing exploitable predictive biomarkers to assess the effects of nutrients was a key result. Furthermore, novel data was obtained on nutrient requirements, especially in the context of using feeds rich in plant protein and oil sources.’ Scientists established new ways to deliver specific micronutrients to modify egg composition or enhance the growth performance of fish-larvae, thereby improving the efficiency of the production process. They could significantly reduce the levels of FM and FO in the feeds of the five species studied without adversely affecting key performance indicators or nutrient utilisation. Greater productivity and improved performance The use of nutritional programming to improve alternative diets in the selected fish species was also investigated. Nutritional programming is based on the idea that differences in nutrition during critical periods in early life can programme an organism’s development, metabolism and health for the future. In addition, a web-based tool that assesses the possible nutrient loadings into the environment was created and made available to all stakeholders. Project partners also designed and delivered training courses in fish nutrition to increase research capacities and expertise, particularly in countries of the enlarged EU. By developing applied tools and solutions of technological interest in collaboration with small and medium-sized enterprises (SMEs), ARRAINA generated new knowledge and strengthened the links between the scientific community and the EU feed industry. This will contribute to the increased productivity and performance of the aquaculture sector, leading to competitive advantage to the whole sector at a global level.
Aquaculture, ARRAINA, biomarkers, micronutrients, nutritional programming