Cold-pressed rapeseed cake as a component of the diet of common carp (Cyprinus carpio L.): effects on growth, nutrient utilization, body composition and meat quality

The aim of the study was to determine the possibility of inclusion of cold-pressed rapeseed cake (CPRC) in diets for common carp, Cyprinus carpio L. Four isonitrogenous (322 g kg−1 crude protein) and isoenergetic diets (17.5 MJ kg−1) with four levels of CPRC incorporation 0, 110, 220 and 330 g kg−1 (treatments RC0, RC11, RC22 and RC33, respectively) were evaluated in a 50-day growth test with common carp of 500 g initial weight. Statistically significant higher final weights (1215–1243 g) were obtained in fish fed diets including CPRC. Fish growth rates were nearly identical in all treatments (specific growth rate of 1.7–1.8% day−1). Similar results were obtained in respect of feeding coefficients (FCR) that ranged from 1.6 to 1.8. Crude protein and ash concentration in fish bodies did not change. Statistically significant decreases in moisture content were found in carp in groups RC22 and RC33. Statistically significant increase of crude lipid in fish bodies were found in groups RC22 and RC33. The slaughter traits and meat quality analysis of carp did not show significant differences. We conclude that it is possible to include up to 330 g kg−1 of CPRC in diets of 2-year-old common carp without significant effects on growth and food utilization.