A standard commercial ration contai

A standard commercial ration containing crude protein, crude lipid, vitamins, and minerals that met the basic dietary requirements of O. niloticus was prepared as shown in Table 1. The ingredients were mixed mechanically at room temperature by horizontal mixer (Hobarts model D300-T, Troy, OH, USA). SP treated diets were prepared by mixing separately a graded
concentration of SP at 5, 7.5, 10, 15, and 20 g/kg diet. The pellets were then prepared using a pellet-machine (California Pellet Mill, Roskamp Huller Co., California, USA) with 0.5 cm diameter. The pellets were left for 24 h for air-drying at room temperature (26 C), broken into small pieces, and sieved to obtain the appropriate size. The rations were transferred into plastic bags and stored in a refrigerator at 4 C until used.The last group was assigned to a control ration and received the standard commercial pellet without any treatment. The required diet was prepared biweekly and stored in a refrigerator (4 C) for daily use.