Brewery by-products (yeast and spent grain) as protein sources in gilthead seabream (Sparus aurata) feeds

Abstract

Two trials were conducted to test the effect of partial replacement of fishmeal by two brewery industry by-products, yeast and spent grain, included in isoproteic and isolipidic diets for gilthead sea bream (Sparus aurata), having in mind the commercial availability of these by-products. According to the obtained results, the inclusion of up to 30% brewers' spent yeast and 15% spent grain in the feed for gilthead seabream gave similar results in terms of growth, food conversion and fillet final composition to a feed with fish meal as the main protein source and show a protein digestibility of 89–95%. Taking into account that these by-products are produced in large quantities in Europe, they can be a potential source of protein to reduce the use of plant proteins or fish/animal by-products (trimmings) and increase the sustainability of both sectors, brewery industry and aquaculture.