effects of palm kernel cake (pkc) on growth performance, blood components and liver histopathology of sex reversed red tilapia (oreochromis niloticus)

Effects of Palm Kernel Cake (PKC) on growth performance, blood components and liver histopathology of sex- reversed red tilapia Oreochromis niloticus were studied using seven isocaloric diets (3400 kCal/ kg) containing different levels of protein and PKC. Diet 1, 2 and 3 contained 20% protein with the supplementation of 15, 30 and 45% PKC, respectively. Diets 4, 5 and 6 contained 24% protein in combinationwith the same PKC supplemention levels mentioned above, and diet 7 was commercial feed containing 20% protein as a control diet. Experimental diets were fed to experimental fish of 48.65 g initial average body weight cultured in floating cages (3 cages/diet) for 10 weeks. Fish fed diets containing higher protein (24%; diets 4, 5 and 6) had significantly better growth performance (p<0.05) than those fed lower protein (20%; diets 1, 2 and 3). Considering the effect of PKC, fish fed diet 5 (Prot. 24%, PKC 30%) gave the greatest growth performance (p<0.05) and all the PKC-fed groups had significantly higher growth than fish fed control diet. There was evidence that supplementation of PKC in fish feed ranging from 15 to 45% had no effect to the survival rate, blood components, or hepatocytic cells of tilapia. However, liver tissue showed higher numbers of lipid droplets in fish fed diet contained 45% PKC (diets 3 and 6). For the production cost, all test diets with PKC supplementation had significantly higher price (p<0.05) than commercial feed. However, when considering the feeding cost per unit of fish production, fish reared with PKC supplemented diets had significantly lower cost (p<0.05) than fish fed commercial feed.