One step toward aquaculture sustainability of a carnivorous species: Fish meal replacement with barley protein concentrate plus wheat gluten meal in Caspian brown trout (Salmo trutta caspius)

Abstract The present study evaluated the effect of replacing fish meal (FM) with barley protein concentrate (BPC) plus wheat gluten meal (WGM) on growth performance, carcass composition, digestibility, digestive enzyme activities, amino acid, and fatty acids profile of Caspian brown trout as a slow-growing and carnivorous fish species. Five experimental diets including Control (0 g/kg BPC), 25BPC (165 g/kg BPC), 50BPC (330 g/kg BPC), 75BPC (495 g/kg BPC), and 100BPC (660 g/kg BPC) were formulated. Also, WGM was added to diets to make them isonitrogenous. A total of 300 fish (13.53 ± 1.1 g) were farmed in three replicates per treatment for eight weeks. Results showed that FM could be replaced by BPC up to 50 % without any negative effect on growth performance (330 g/kg FM, 330 g/kg BPC). Fish was fed with dietary Control, 25BPC, and 50BPC digested protein and energy significantly better than those fed other diets. Accordingly, there were negative linear relations between BCP level in diets and trypsin, pepsin, and aminopeptidase activities (P