Effects of duration of a plant-based diet stimulus at first feeding on nutritional programming in Atlantic salmon (Salmo salar)

Nutritional programming could potentially be a strategy for the sustainable aquaculture, as it can adapt fish to feeds formulated with low levels of marine ingredients. The present study aimed to determine the effects of the early dietary stimulus duration, and to reveal the impacts of a later challenge with a similar diet. At first feeding, Atlantic salmon ( Salmo salar ) fry were fed a plant-based diet for either one (V1) or two weeks (V2), while a control group received a marine diet for the two weeks (M). All fish then received a marine diet for 16 weeks before being challenged with a plant-based diet for 6 weeks. All fish received the same diet with the only difference between the three experimental groups (V1, V2 and M) being their dietary regime during the first two weeks. Duration of the stimulus had no phenotypic impacts on growth, tissue fatty acid compositions of either total or polar lipid in all groups after challenge. The expressions of key genes of LC-PUFA biosynthesis were upregulated significantly in salmon from the V1 group, whereas the expressions of most transcription factors were downregulated in fish of group V2. Histological analysis of the intestine revealed increased circular muscle thickness and reduced presence of goblet cells in V1 after the challenge. Overall, further investigation is required to establish the appropriate duration of the stimulus to elicit positive effects and refine the use of nutritional programming in Atlantic salmon, including the effects of short stimuli and assessment with longer challenge.