Effect of plant protein-based aquafeeds on zebrafish growth and health at the molecular level

For the sustainable growth of Norwegian aquaculture industry, exploration of novel protein sources for fish feed is a necessity due to the limitation of marine fish meal resources. Currently, the Norwegian salmon aquaculture industry uses up to 70% of plant materials in feeds, compared to 10 % in 1990. This huge transition from fish meal to green diets has led to new challenges in fish health and welfare, as well as product quality. Some of these issues have been addressed by extensive research, but very little is known about the molecular effect of plant ingredients on fishes. Therefore, this project aims to study the effect of plant protein-based aquafeeds on fish growth and health at the molecular level by exploring global transcriptome and epigenome changes using zebrafish as a model. As we will apply commonly used plant proteins in aquafeeds, up to 30% in the diets, little distress is expected. We plan to use the minimum number of zebrafish required to test low and high levels of three plant ingredients in comparison with a control diet with marine proteins to achieve significant results, i.e. 336 animals. The 3R principles have been addressed by i) performing feeding trials for a minimum duration to accomplish significant results, ii) Obtaining more information from the same experiment by sharing the biological samples with a collaborative project, iii) utilising the same biological material for multiple molecular analysis, iv) humanely sacrificing the fish with an overdose of anaesthetic. This experiment is linked to the EPIGREEN AND SAFEFISH projects funded by the Research Council of Norway under the HAVBRUK programme. The expected results will provide the first evidence that plant ingredients may induce epigenetic modifications leading to alterations in transcript levels associated with fish health and growth performance. This knowledge can be extended to Norwegian aquaculture industry by testing selected molecular markers from the zebrafish model on on-growing Atlantic salmon fed with green diets. Ultimately, it will also help to address the fish welfare concerns in general public regarding forcing fish into a vegetarian diet.