It is widely recognized that stress has profound effects on the immune system of fish. Although actions are undertaken to minimize stress and adverse effects during aquaculture production mitigation strategies are necessary when stress cannot be avoided. A variety of stressors impact health and performance of Atlantic salmon produced in intensive land-based recirculating aquaculture systems (RAS). Among them oxidative stress occurs during the regular disinfection of RAS facilities and is induced by strong oxidants such as peracetic acid (PAA) . Besides its beneficial effects PAA alters the stress and immune response of Atlantic salmon [2,3]. Dietary mitigation strategies may prove useful under these conditions in mitigating the effects of such oxidative acute stress. In this study we explored whether differently applied microalgae enriched functional feeds influence the immune and stress response of Atlantic salmon towards an acute oxidative stress (PAA treatment).
Material & Methods
Atlantic salmon smolts (20 per tank, initial weight ~ 126 g) were reared in triplicates in a recirculating aquaculture system. The fish were fed either a control diet (CD), a diet containing 2 % (CV2) or 14 % (CV14) of Chlorella vulgaris on a daily basis, or the diet containing 14 % Chlorella vulgaris once weekly (CV14w). Following eight weeks of feeding, all groups were subjected to an acute oxidative stress induced by treatment with peracetic acid (WOFA-steril, Kesla, Germany) at 2.5µl PAA / L water. We assessed growth performance plasma stress indicators as well as gene expression of stress- and immune-related genes in the head kidney and gill.
Results & discussion