Potential of poultry by-product meal as a substitute for fishmeal in diets for Black Sea turbot Scophthalmus maeoticus: Growth and nutrient utilization in winter

The use of poultry by-product meal as an alternate dietary protein for Black Sea turbot Scophthalmus maeoticus (initial avg wt 18 g) in winter was evaluated. Triplicate groups of 15 fish were fed one of five isoenergetic (gross energy 20.5 +/- 0.21 kJ/g) and isonitrogenous (protein content 55 +/- 0.35%) diets with 25%, 50%, 75%, or 100% of the fishmeal protein replaced by poultry by-product protein. White fishmeal was the sole protein source in the control diet. There was no significant (p < 0.05) reduction in growth performance of the turbot fed the 25% replacement diet compared to the control diet (100% fishmeal). At the replacement levels of 50%, 75%, and 100%, however, there was a severe decrease in feed intake, growth performance, feed utilization, protein efficiency ratio, and apparent net protein utilization. Results indicate that up to 25% of the fishmeal protein can be replaced by poultry by-product meal with no negative effects in fish performance at temperatures ranging 6-8 degrees C.