An 8-week feeding trial was conducted to determine the dietary arginine requirement of juvenile black sea bream Sparus macrocephalus in 18 350 L indoors £ow-through circular ¢breglass tanks. Six isonitrogenous and isoenergetic diets were formulated to contain graded levels of L-arginine (1.85%, 2.23%, 2.51%, 2.86%,3.20% and 3.46% dry diet) from dietary ingredients and crystalline arginine. Each diet was randomly assigned to triplicate groups of 25 juvenile ¢sh (10.51 AE 0.15 g) twice daily (08:00 and 16:00 hours) to apparent satiation. Results showed that the speci¢c growth rate (SGR) increased with increasing dietary arginine levels up to 2.51% and remained nearly the same thereafter. Feed e⁄ciency ratio, protein e⁄ciency ratio (PER) and protein productive value all showed an increasing tendency and then levelled o¡. Apparent digestibility coe⁄cients of dry matter, crude protein and gross energy signi¢cantly improved up to 2.86% arginine diet and decreased at di¡erent extents thereafter. Fish fed 1.85% arginine diet had signi¢cantly lower protein content in the whole body and dorsal muscle than those fed diets supplemented with or 42.86% of arginine. Lipid content decreased and lower value occurred at 3.46% of dietary arginine. The dietary essential amino acid composition in the whole body of the black sea bream was signi¢cantly in£uenced by dietary arginine. Arginine retention increased with an increasing dietary arginine level from 1.85% to 3.20%, then declined slightly at 3.46% arginine diet. Serum biochemical parameters were signi¢cantly a¡ected by the dietary arginine level except for the cholesterol content. Broken-line regression based on SGR and second-order polynomial regression based on PER indicated that the optimum dietary arginine requirements for juvenile black sea bream were 2.79% and 3.09% diet, corresponding to 7.74% and 8.13% of the dietary protein respectively. , 320 and p-aminobenzoic acid, 50. zOthers (%) : carboxymethylcellulose, 4; sodium dihydrogen phosphate, 2.5; k-carrageenan, 2.5; a-cellulose, 5.08; betaine, 0.3; Cr 2 O 3 , 0.5. ‰Values for the proximate analysis of the test diets are means of triplicate analyses. Optimum arginine requirement of black sea bream F Zhou et al. Optimum arginine requirement of black sea bream F Zhou et al. r 2010 The Authors Aquaculture Research r 2010 Blackwell Publishing Ltd, Aquaculture Research, 41, e418^e430 e421 Ã Values are presented as mean AE SD (n 5 3); values with di¡erent superscripts in the same row di¡er signi¢cantly (Po0.05).Survival (%) 5 100 Â ¢nal ¢sh number/initial ¢sh number; WG (weight gain) (%) 5 100 Â (FBWIBW)/IBW; SGR (speci¢c growth rate) (% day À 1 ) 5 100 Â (ln FBWln IBW)/day; CF (condition factor) (g cm À 3 ) 5 100 Â (live weight, g)/(body length, cm) 3 ; HSI (Hepatosomatic index) 5 100 Â (liver weight, g)/(body weight, g); FER (feed e⁄ciency ratio) 5 100 Â wet weight gain in g/dry diet fed in g; PER (protein e⁄ciency ratio) 5 weight gain in g/protein intake in dry basis in g; PPV (protein productive value) 5 g protein gain/g pr...

The 8-week experiment was conducted to evaluate the effects of partial replacement of fish meal (FM) with soybean protein concentrate (SPC) on juvenile black sea bream, Acanthopagrus schlegelii (10.70 ± 0.04 g). Diets were formulated to replace FM protein by SPC at 0, 8, 16, 24, 32 or 40% (designated as T1, T2, T3, T4, T5 and T6, respectively). Diets except T1 were supplemented with phytase at 2000 phytase activity U kg )1 . The results showed that survival rate, growth performance and feed utilization were not significantly affected by increasing dietary SPC. Fish fed diet T3 had higher feed intake compared to those fed T1, T2 and T5 diets. Whole body compositions of black sea bream were significantly influenced by SPC replacing FM except for protein, ash and phosphorus content. Condition factor of fish was significantly lower in T2 than that of fish in T3 group. Apparent digestibility coefficients (ADCs) of dry matter was higher in fish fed T6 diet than those of fish fed T1 and T2 diets, ADCs of phosphorus increased with dietary SPC level up to T3 and then decreased. The results obtained in this study indicate that FM protein could be effectively replaced by SPC protein with phytase in diet of black sea bream. KEY WORDS