| dc.description.abstract | In many countries, aquaculture is key for giving essential food security and income. As the human population grows, an upscaling and reshaping of aquaculture is required to meet the increasing demands for seafood in the future. Sustainable future aquaculture feeds should therefore support fish health and resilience through strategic functional nutrition. The addition of immunostimulants and antioxidants in the feed can improve fish health at stressful times. The interest for in vitro methods as research tools in aquaculture is greatly increasing, as economical, practical, and ethical alternatives to in vivo trials. The use of intestinal cell lines shows promise by modeling the gut and therefore enabling the study of the impact of functional fish feed additives. This thesis focused on the development of an in vitro screening method, based on cytotoxicity/cell viability and reactive oxygen species assays, to study the effect of several feed ingredients, namely vitamin C, -glucans, sodium butyrate, saponins and two undisclosed factors F and Y, on the rainbow trout intestinal epithelial cell line (RTgutGC). The aim was to investigate the cellular responses triggered by these feed additives, which can then give valuable information for novel feed formulations. Concentrations of 1 and 10 µM/mL of vitamin C and 1000 µg/mL of the -glucan (MacroGard®) showed significantly lower cell viability compared to the control. None of the tested concentrations of sodium butyrate, factors F and Y showed an adverse effect on cell viability. When exposed to 200 and 2000 µg/mL of saponins, RTgutGC cells indicated cytotoxicity compared to the control. The concentrations found to significantly reduce the reactive oxygen species generation in the RTgutGC cells individually were 500 and 1000 g/mL of -glucans, 0.2 and 2 mM of sodium butyrate and 5000 µM of vitamin C. A wound healing assay demonstrated that 2 and 10 mM of butyrate, 200 µg/mL of saponins and 10 µg/mL of factor Y showed a significant decrease in proliferation rate. The obtained results support the suitability of in vitro method using RTgutGC as a valuable alternative tool to in vivo trials. Indeed, it deepens the understanding of the many mechanisms of action in which different additives partake when being incorporated into fish feeds. | |