EVALUATION OF THE ACUTE AND CHRONIC IMMUNE RESPONSE OF SALMONIDS AFTER BEING FED A PLANT PROTEIN-BASED FEED

Ken Overturf, Thomas Welker, Madison Powell
ken.overturf@ars.usda.gov
 

Even though fish meal and fish oil have proven to be ideal protein and oil sources for aquaculture, as production continues to grow, the scarcity of these fish-derived products makes them less than ideal as protein and oil sources in aquaculture feeds. The use of plant proteins and oils are seen as economical and sustainable replacements. However, intestinal inflammation and other symptoms are known to occur when carnivorous fish species are fed feeds with partial or complete fishmeal replacement using certain plant-based protein sources. To decipher the immunological and stress responses in these species, we fed a domesticated stock of rainbow trout (CL), and a strain of rainbow trout that has been selected to utilize soy-based feeds without developing enteritis (SEL), either a fishmeal or plant-based feed for 7 months. Significant differences were found for weight gain between the groups (Figure 1). Samples of gill, spleen, kidney, intestine and liver were taken at 3 and 7 months of feeding for RNA isolation and gene expression analysis. Furthermore, subgroups of these fish were all subjected to a stressor at 3 and 7 months, and the same tissues were sampled to determine the effect of diet and strain on stress responses. Obtained samples were analyzed for the expression of genes involved in either the cellular or humoral immune response and stress response.