COMPARATIVE GROWTH PERFORMANCE AND FEED UTILIZATION OF FOUR LOCAL STRAINS OF NILE TILAPIA (Oreochromis niloticus L.) COLLECTED FROM DIFFERENT LOCATIONS IN EGYPT

Brood stocks of Nile tilapia, Oreochromis niloticus L. were collected from Lakes Nasser (Aswan), Manzalah, Maryut, and Abbassa fishponds. Fingerlings of F1 of each strain were fed diet containing 27 % CP for 90 days. The results showed that Aswan strain was superior to other tilapia strains in growth performance. Survival rate was not significantly different among Nile tilapia strains. Crude protein contents in fish body was insignificantly different among Abbassa, Aswan and Manzalah strains, whereas the less protein content was observed in Maryut strain. There was no significant difference in total lipids content in Abbassa and Manzalah strains and between Aswan and Maryut strains. Ash content did not significantly differ in all tilapia strains. The highest feed intake was observed in Aswan strain, while there was no significant difference in feed intake among other tilapia strains. The lowest FCR value was obtained in Aswan strain, whereas the higher ones were obtained in Abbassa and Manzalah strains. The maximum PER was recorded in Aswan strain, while the less ones were obtained in Abbassa and Manzalah strains. The maximum PPV value was obtained in Manzalah strain, whereas the lowest was observed in Abbassa strain, and there was no significant difference between Aswan and Maryut strains. It could be concluded that Aswan strain was more efficient in feed utilization and protein turnover than the other strains where higher growth performance with higher PER and lesser FCR values were observed in Aswan strain