Addressing the global food security challenge : discovery and assessment of sustainable sources of ingredients for aquaculture feed

The world faces the grand challenge of supplying enough food to achieve food security for its rapidly growing population, predicted to reach 9 billion by 2050. Animal meat is an important part of the human diet, despite the global livestock population containing almost 24 billion animals, it is estimated that total food production will need to increase by 70 % to supply the 2050 population. Fish is a highly nutritious food item associated with several health benefits. Global consumption of fish, which is increasing, now constitutes 17 % of animal protein intake. Fish supplied through capture is limited by wild stocks; in 2015 aquaculture was responsible for 53.1 % of fish and seafood produced globally. The aquaculture industry is reliant on fishmeal and fish oil as ingredients for aquafeeds, materials produced from wild stocks or industry waste trimmings; these are finite and costly ingredients. There is great desire to identify cheaper more sustainable ingredients. In order for alternative ingredients to be viable for fish feed inclusion they must be palatable and of sufficient nutritional quality. The aim of this study was to identify alternative ingredients and assess them, through palatability and performance, for aquafeed inclusion. Several alternative ingredients were identified, Natto (fermented full fat soybean), fermented Rapeseed meal, fermented potato protein concentrate (PPC) (all subjected to heating and fermentation to improve nutritional quality), NH Algae (New Horizons Global Ltd Schizochytrium microalgae NHG-002) , Mealworm meal (Tenebrio molitor), Silkworm meal (Bombyx mori), and Earthworm meal (Eisenia fetida). These were tested for palatability using a modified method of behavioural observation based on the work of Alexander Kasumyan, and by analyses of the satiety hormone Cholecystokinin (CCK), released in response to feed. They were then tested in nutritionally balanced feeds for growth and performance in zebrafish (Danio rerio) an as initial model species, then in commercially relevant and available species, while partially or completely removing fishmeal and fish oil. Palatability testing via behavioural observation was applied to three species; alternative ingredients were accepted, with only Natto and PPC showing reduced taste response compared with other materials. CCK analyses proved possible, although further development is required in order to identify any significant differences between the responses measured. Growth and performance trials showed that the NH Algae, Natto and Rapeseed meal materials can be included in species specific diets to partially reduce fish meal. The invertebrate meals when used together successfully removed fishmeal completely in diets of three species tested, achieving equal growth and equal or improved performance. Fish oil was only partially reduced with the inclusion of NH Algae, and by Natto in trout diets, the insect diets provided high amounts of linoleic and a-linolenic acid but failed to supply EPA or DHA. This project introduces novel approaches to assess palatability and shows that invertebrate meals have the greatest potential for complete removal of fishmeal, however, fish oil is still required until a suitable source of EPA and DHA can be identified.