Using Different Feeding Rates to Determine Protein and Energy Maintenance and Maximum Growth Requirements for European Sea Bass (Decentrarshus Laborax) Fingerlings = تقدير احتياجات إصبعيات أسماك القاروص الحافظة والإنتاجية من البروتين والطاقة باستخدام معدلات تغذية مختلفة

The effect of feeding rates (2, 3, 4, 5, 6 and 7%) was studied on growth performance, body composition and feed utilization of European sea bass (E. sea bass) ( Dicentrarchus labrax ) fingerlings in saltwater 30 ppt and temperature 27.8ºC. Protein and energy requirements for maintenance and maximum growth were also determined. Fish were fed on a basal diet containing 35.5% crude protein and 285 kcal ME / 100g diet. Fingerlings (3.1 g ± 0.05) initial average BW were stocked at the rate of 10 fish per aquarium. Fish were fed 3 times daily; the amount was adjusted every Ten days according to the determined biomass per each aquarium. Weight gain and final body weight (FBW) of E. sea bass increased significantly with increasing dietary feeding rate from 2 up to 4 % with no differences among 3, 5 ,6 % and 7%. The best growth and specific growth rate were observed with 4% feeding rate and no significant differences were found with increasing FR beyond 4%. The body weight, body protein and energy of sea bass increased by increasing protein and energy intake in the diet from (6.75 to 14.2 mg protein / 1g BW daily and from 82.14 to 192.8 cal. gross energy / 1g BW daily). The increase in body weight gain (Y 1 ), body protein and energy (Y 2 ) with the increase of protein and energy intake could be expressed by the equations: Y 1 = - 302.31 + 259.41 X: Y 1 = -302.31 + 20.18 X; Y 2 = - 47.17 + 49.48 X; Y 2 = - 676.78 + 39.22X for protein and energy, respectively. From the regression analysis, maintenance requirements could be calculated at Y= zero. They were in average found to be 1.06 mg protein /g BW and 16.11 cal. gross energy/g BW daily for E. sea bass (3.1g IBW). The result indicates that the best feeding rate was found at 4% BW for sea bass 3.1g IBW. With maximum growth requirement of 14.2 mg protein/g BW and 192.8 cal. gross energy/g BW.