Increasing demand for conventional fish feed ingredients has resulted in rising fish feed costs, which are considered a hindrance to the aquaculture industry’s growth. Brewer’s spent grains (BSG) are byproducts that are not suitable for human consumption and whose safe disposal raises environmental concerns. Brewer’s waste is one of the promising protein source by-products for fish diets.
An 8-week feeding trial was conducted at Kentucky State University Aquaculture Research Center to assess the nutritional value of practical diets containing different amounts and combinations of BSG and Allzyme® SSF in Nile tilapia (Oreochromis niloticus). A factorial design was used, with three levels of BSG (0, 270, and 550 g/kg) and three levels of ENZ (0, 0.2, and 0.4 g/kg) being used to examine the fish’s production performance and whole-body proximate composition. At the conclusion of the study, linear reductions in growth of the fish as dietary BSG increased were observed, while no significant effects of ENZ or interactions between ENZ and BSG were found for all response parameters evaluated. Further studies are recommended to define optimal dietary levels of BSG and enzymes that degrade non-starch polysaccharides in these species’ feeds.