Effects of incorporating in diets cold-pressed rapeseed cake on the growth performance, nutrient utilization, and body composition of common carp (Cyprinus carpio L.)

Alternative proteins from vegetal sources are being studied, because of the high costs and limited resources of fish meal. The aim of this study was to determine the possibility of including cold-pressed rape cake (CPRC) as a partial protein substitute in diets for common carp, Cyprinus carpio L. Common carp fry were stocked into experimental ponds at a density of 30 fish per pond. The effects on growth, feeding efficiency, and fish body composition were studied for four amounts of CPRC (0, 70, 130, 200 g × kg^-1). Statistically significant higher final weights (528-530 g) were obtained with fish fed diets with 130 and 200 g × kg^-1 CPRC. The fish growth rate was nearly identical in all variants (SGR of 3.3-3.4 % d^-1). Similar results were presented in FCR at 1.3, and in PER at 2.2. Our results suggest that it is possible to include up to 200 g × kg^-1 of CPRC in diets for two-year old common carp without significant effects on growth, nutritive efficiency, or the proximate composition of the fish.