GLUTEN-FREE FISH: DIET AND INFLAMMATION IN EUROPEAN SEA BASS Dicentrarchus labrax

The aquaculture industry is rapidly expanding to feed a burgeoning world population. The unsustainability of harvesting small ocean forage fish to feed aquaculture fish has precipitated the increased incorporation of plant proteins. A variety of these ingredients including low-fat, high-protein concentrates derived from plants such as wheat (including processed gluten) have been successfully incorporated into fishmeal-free diets for a variety of cultured species.

Though wheat gluten may be well tolerated in some species, several studies conducted by the Place laboratory bring into question its use in formulations designed for feeding of young cobia (Rachycentron canadum). Dietary wheat gluten in even small quantities (< 3%) contributed to either sub-par performance or low survival in small juveniles of ~8-10 g starting weight. Suspecting that carnivorous species might be more sensitive to this ingredient, we implemented a dietary study in European sea bass using plant-based formulations with and without added wheat gluten. Due to the lack of fish meal, we supplemented the diet with taurine, which had proven to be an essential amino acid for cobia. European sea bass was chosen for study as another carnivorous species that  was easily available and had published genomic data that would allow us to probe for specific immune mediators.

A six-month dietary study showed that European sea bass growth is equivalent on plant-based diets with or without 4% added wheat gluten (see figure). To assess any immune reactions or changes to overall health in response to dietary wheat gluten that did not result in changes in weight, we will probe for markers including C-reactive protein, tumor necrosis factor-α, interleukin-1β, IgM, and IgT. Changes to blood chemistry indicative of changes to overall health will be evaluated, including aspartate aminotransferase and alanine aminotransferase for liver function and urea and creatinine for kidney function. In addition, we will evaluate alterations to the gastrointestinal tract with regards to molecular markers, histology, and the microbiome.