Slaughter value and flesh characteristics of European catfish (Silurus glanis) fed natural and formulated feed under different rearing conditions

The experimental material was comprised of European catfish (Silurus glanis) individuals aged 2.5 years that were reared on natural feed in earthen ponds and individuals aged 1.5 years cultivated intensively on formulated feed in recirculating systems. Weight gain and morphometric parameters were measured along with physical and color characteristics and proximate composition of fillets. Despite the different age and diets of the fish, no differences were observed in the linear biometric indices. The total weight of the fish of both groups and their condition coefficients were also similar. In addition, no differences were reported in their body weight or head and gutted (H&G) carcass and fillet yields. Proximate composition analysis demonstrated a lack of differences in the contents of dry matter. Of the dry matter, differences were reported in the fat content, which was higher in the catfish fed formulated feed. The color of the fillets was characterized by high values of lightness, negative values of redness, and positive values of yellowness, and the fish fed formulated feed displayed higher saturation of green. The flesh of both groups of catfish demonstrated similar pH values and water retention capacity, whereas the values of thermal drip appeared to be higher in the fish fed formulated feed.