• Journal of Aquaculture
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• v.21 no.4
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• pp.244-251
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• 2008

We evaluated the optimum dietary lipid level and feeding rates of extruded pellets (EP) in juvenile flounder Paralichthys olivaceus during the summer season. The first experiment was conducted to determine the optimum dietary lipid level in juvenile flounder. Five isonitrogenous EP (52% crude protein) with increasing dietary lipids (6, 8, 10, 12 and 14%) were fed to satiety to triplicate groups of the juveniles ($18.4{\pm}0.11g$) twice a day for 6 weeks. Weight gain (WG) of fish fed EP with 10% lipid was significantly higher than those of fish fed EP with 6 and 14% lipid (P<0.05). Broken line model analysis suggested that the optimum dietary lipid level could be $9.08{\pm}0.37%$ for the maximum WG in juvenile flounder. The second experiment was conducted to determine the optimum feeding rate using experimental diet contained 10% lipid level that had the highest WG in first experiment. The feed intake of triplicate groups of the juveniles ($13.4{\pm}0.15g$) was restricted to four different feeding rates of 2.0, 2.5, 3.0 and 3.5% of their body weight $day^{-1}$ and to satiation using experimental diets. WG and feed efficiency (FE) of fish was affected by feeding rates. WG and specific growth rate of fish fed the diets increased with increasing feeding rate, however no significant differences (P>0.05) in WG and specific growth rate were observed between the fish fed 3.5% of their body weight $day^{-1}$ and to satiation. FE of fish fed 3.5% of their body weight $day^{-1}$ was significantly higher than those offish fed 2.0% of their body weight $day^{-1}$ and to satiation (P<0.05). Broken line model analysis suggested that the optimum dietary feeding rate could be $3.56{\pm}0.06%$ for the maximum WG in juvenile flounder. These results indicated that the optimum lipid level and feeding rate could be $9{\sim}10%$ (Energy: 4,774kcal and PIE ratio: 108mg protein/kcal in diet) and 3.5% of their body weight $day^{-1}$in juvenile flounder, respectively.

• Journal of Aquaculture
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• v.18 no.3
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• pp.160-166
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• 2005

Two feeding trials were carried out to investigate apparent nutrient digestibility of flounder fed experimental diets containing different levels of macro-nutrients by satiation feeding rate (Exp-1) and feeding frequency (Exp-2). Triplicate groups of fish averaging 280 g were fed three experimental diets which contained different levels of carbohydrate, protein and lipid by two feeding regimes (satiation and 80% satiation) and four feeding frequencies (three meals a day, two meals a day, one meal a day and one meal every two days). Feces were collected using a fecal collection column attached to fish rearing tanks for 6 weeks. Apparent digestibilities of dry matter, protein, lipid, energy and carbohydrate were not affected by feeding satiation rate in Exp-1. Apparent protein digestibility was not affected by feeding frequency, whereas affected by dietary composition in Exp-2. Apparent protein digestibility of fish fed a high-protein diet showed a tendency to become higher compared to that of fish fed high-carbohydrate diet and high-lipid diet at the same feeding frequency. Apparent lipid digestibility was not affected by dietary composition, however, affected by feeding frequency. Apparent digestibilities of energy and carbohydrate were affected by both dietary composition and feeding frequency. Apparent digestibities of energy and carbohydrate in fish fed the high-protein diet showed a tendency to become higher compared to that of fish fed the high-carbohydrate diet and high-lipid diet at the same feeding frequency. Apparent digestibities of energy and carbohydrate tended to decrease with increasing of feeding frequency at the same dietary composition.