Test Experiments were carried out to design, manufacture and evaluate the performance of a cooking unit used for rendering poultry abattoir residues (intestines and legs residues) and investigate the effect of using these by-products in feeding Nile tilapia fish. The performance of the manufactured cooker was studied under the following parameters: Three different poultry abattoir treatments were 100% intestines, 50% legs + 50% intestines and 100% legs under four different agitating speeds 20, 30, 40 and 50 rpm and was evaluated taking into consideration the following indicators: productivity, cooking efficiency, total losses, specific energy and criterion costs through the first experiment. With regard to the second experiment was aimed to investigate the effect of different levels of poultry by-product meal on the feed utilization and whole-body composition of Nile tilapia fish. Growth performance was studied taking into consideration both of feed efficiency ratio and protein efficiency ratio. The results reveal that the highest values of machine productivity and cooking efficiency were (52.30 kg.h^-1 and 97.90%), while the lowest values of the total losses and criterion cost were (2.10% and 1500 LE.Mg^-1), respectively under agitating speed of 40 rpm with adjusting vapor pressure on 2 bar using 50% intestines + 50% legs residue.  Furthermore, the obtained results show that there is no difference in growth performance and feed utilization between Nile tilapia fish when feeding on diets have 25 and 50% of poultry by-product meal i.e. 75 and 50% of fish meal.