EFFECT OF EXTENDED FEEDING WITH LIVE COPEPODS, OITHONA NANA, AND ARTEMIA FRANCISCANA ON THE GROWTH PERFORMANCE, INTESTINE HISTOLOGY, AND ECONOMIC VIABILITY OF EUROPEAN SEABASS (DICENTRARCHUS LABRAX) POSTLARVAE

To improve the efficiency of rearing and minimize the production cost of European seabass (Dicentrarchus lahrax) postlarval stage, the present study was designed to evaluate the extended use of live copepods, Oithona nana, and live Artemia franciscana compared to an artificial weaning diet. The larvae fed the artificial weaning diet referred as the control, the other six groups were fed live copepods and artemia as live feed in two concentrations each (1 and 2 individual/ml) or a mix of both live feeds (0.5 + 0.5 ind./ml, and 1 + 1 ind./ml, respectively). The experiment consists of two phases. In phase I, postlarvae were fed an artificial weaning diet in seven experimental regimes for 30 days at feeding rates adjusted to 12% live body weight in the control and 6% artificial weaning diet plus live feed in the other sex groups. In phase II, all seven experimental groups were fed the artificial weaning diet only at a feeding rate adjusted to 9% of live body weight for a further 40 days. The results revealed that the fatty acid profile of live copepods, including PUFA and Σ n3 is higher than that of artemia by 26.47 and 36.30%, respectively. The growth performance, feed utilization, and survival improved significantly in all live feed groups compared to the control group. The histological investigation of proximal intestine showed an increase in the mucous cells and mucosal folds in the proximal intestine of postlarve fed cope-pods and artemia compared to the control. The lowest incidence cost and highest profit index were recorded with postlarvae fed copepods. Therefore, the results demonstrate that due to their high nutritional value and low production cost compared to A. franciscana, and weaning diet, copepod. Copepods, O. nana, could be considered as a potential alternative live feed for D. labrax.