Improved understanding of fish digestion helps aquaculture swallow sustainable feeds
Fish farms are set to become the main producers of seafood, overtaking traditional capture fishery. They have the potential to relieve the pressure on dwindling fish stocks, but the feed used (aquafeed) is often based on smaller, wild species. More sustainable plant-based options are available, but the nutritional content is not the same, and can impact fish production. Fortunately, aquafeeds are becoming more sustainable, as fish meal and fish oil are increasingly replaced by alternative ingredients for the main farmed species. In addition, there is an increased focus to reduce nitrogen and phosphorus waste and improve feeding strategies. However, work still needs to be conducted on aquafeeds to better understand their impact on production and optimise the digestion process to promote lean growth among farmed fish. Knowledge gap addressed The EU-funded WiseFeed project addressed this challenge by building an integrated network of research groups drawn from academia, and partners from SME’s and large enterprises. Their overall aim was improving the performance and sustainability of aquafeeds for fish production. This research was undertaken with the support of the Marie Curie programme. Optimisation of the digestion process is crucial for sustainable fish farming and depends on a series of integrated physiological processes including ingestion, secretion, digestion, absorption, motility and evacuation. “However, knowledge on the overall processing capacity of the digestive system for nutrients in key aquaculture fish species is still fragmentary and incomplete and therefore limited. There is the lack of a global perspective on the different mechanisms modulating nutrients absorption and utilisation,” says project coordinator Prof. Ivar Rønnestad. Multiple benefits Project partners developed simulation models and a software package to optimise feeding strategies. “We created new and improved models for measuring the digestion, absorption and retention efficiency of selected macro nutrients in key cultured fish species,” explains Prof. Rønnestad. “We also studied in detail the role of methionine, an essential amino acid and integrated this knowledge into our software models,” he adds. An important part of WiseFeed has been the collaboration with partners in Vietnam, enabling European researchers to study cobia, a fast-growing tropical marine species. Warm water species are growing in importance as alternative farmed species in southern Europe and non-continental territories with sub-tropical weather. Their software package “enables users to test the effects of specific amino acids and dietary supplements for enhancing metabolism, growth and nitrogen retention, including the effects of elevated temperatures due to climate changes,” Prof. Rønnestad states. WiseFeed benefits the aquaculture sector by enhancing the utilisation of nutrients, thereby improving production yields while reducing feeding costs, and reducing the environmental impact of released nutrients. “The project will make aquaculture an ever more environmentally friendly industry, while increasing the economic results of fish farming enterprises. It also contributes to the implementation of research findings into the commercialisation of innovative products and services, thereby increasing the competitiveness of European aquaculture,” Prof. Rønnestad comments.
Keywords
WiseFeed, aquafeed, digestion, aquaculture, models, fish farming, amino acids, nitrogen, sustainability, nutrition
