PRELIMINARY STUDY ON GROWTH, FEED CONVERSION AND PRODUCTION IN NON-IMPROVED AND IMPROVED STRAINS OF THE NILE TILAPIA

The culture of an improved tilapia strain characterized with fast growth rate and low feed conversion ratio would have great economic benefit for the farmers by improving the production potential of fresh tilapia. Two experiments were conducted consecutively in triplicates to evaluate and compare the mean weight (MWT), daily growth rate (DGR), feed conversion ratio (FCR), survival and production rate (PR) in the non-improved strain (NS) of the Nile tilapia, Oreochromis niloticus with two selected strains obtained from the Philippines namely the Genetically Improved Farmed Tilapia (GIFT) strain and the FAC selected tilapia referred to as selected line (SL) from the swim-up fry stage to 1.0 g (Experiment 1) and from 1.0 g to 20 g (Experiment 2). The NS served as the control treatment. In Experiment 1, swim-up fry having mean weight of 0.01 g were stocked in 0.12 m3 tanks at density of 1650 m-3, whereas in Experiment 2, fingerlings with 1.37 g mean weight were stocked in 0.42m3 tanks at a rate of 300 fish m-3. The fish in both experiments were hand-fed 4-5 times daily with marine feed (Biomar 50 % crude protein). Water temperature was maintained at 29.0 ± 2.0oC. The two experiments lasted for 42 and 56 days, respectively. In both experiments, results showed significant differences in growth (P<0.05) between the NS group and both the GIFT and SL groups. Both groups had significantly higher MWT, faster DGR, lower FCR and higher PR than the NS group. Unlike in Experiment 1, no significant difference was evident in survival between the three groups. In Experiment 1 the improvement in the SL group over the NS group for the MWT, DGR and PR was 77.9, 72.9 and 33.6%, respectively, whereas in Experiment 2, the improvement for the same parameters were 58.7, 57.8 and 54.5%, respectively. These results demonstrate the advantage and potential of culturing the SL or the GIFT strain in improving the production of fresh tilapia, reducing the production cost and increasing the profitability of tilapia farms in Kuwait