ALBERT

Notes: An experiment was conducted to determine the dietary protein requirement by different analysis methods and to study the effects of dietary protein levels on growth performance and body composition in Japanese flounder Paralichthys olivaceus fed white fish meal and casein-based diets for 8 wk. After a 1-wk conditioning period, one of six isocaloric diets containing 30, 36, 42, 48, 54, and 60% crude protein (CP) was fed to fish at approximately 4–5% of wet body weight on a dry matter basis to triplicate groups of 15 fish averaging 13.3 ± 0.06 g (mean ± SD). After 8 wk of the feeding trial, weight gain (WG) and feed efficiency (FE) from fish fed 48% CP diet were similar to those from fish fed 42% and 54% CP diets, and were significantly higher than those from fish fed 30, 36 and 60% CP diets (P 〈 0.05). Fish fed 48 and 54% CP diets had a significant higher specific growth rate (SGR) than did fish fed 30 and 36% CP diets (P 0.05). Protein efficiency ratio (PER) was inversely related to the dietary protein level. No significant differences existed in hematocrit (PCV) and survival rate among the dietary treatments. Broken-line model analysis indicated that the optimum dietary protein level could be 44.0 ± 3.0% for maximum WG in Japanese flounder. Polynomial regression analysis of the dose-response showed that maximum WG occurred at 50.2% (R2= 0.94) based on WG, and the second-order polynomial regression analysis with 95% confidence limits revealed that the range of minimum protein requirement was between 38.9% and 40.3% based on WG. Therefore, these findings suggest that the optimum dietary protein requirement for maximum growth of Japanese flounder is greater than 40%, but less than 44% CP in the fish meal and casein-based diets containing 17.0 kJ/g of energy.

Notes: The olive flounder Paralichthys olivaceus is one of the most commercially important fish species in Korea. In order to formulate better diets for cultured olive flounder we evaluated the optimum dietary protein requirements for larval, fry and juvenile olive flounder, and the optimum dietary protein to energy ratio for juvenile olive flounder. Results of four separate experiments suggested that the optimum dietary protein requirements were 60% in larvae (0.3 g), 46.4–51.2% in 4.1-g juvenile, and 40–44% in 13.3 g growing olive flounder. The optimum dietary protein to energy ratio based on weight gain, feed efficiency, specific growth rate, and protein retention efficiency was 27–28 mg protein/kJ 2 energy (35 and 45% CP for diets containing 12.5 and 16.7 kJ energylg diet, respectively).

Notes: An 8-wk feeding trial was conducted to estimate the optimum dietary protein level and protein-to-energy (P/E) ratio in juvenile Korean rockfish Sebastes schlegeli. Twenty experimental diets were formulated with four energy levels and five protein levels at each energy level. Four gross energy levels of 14.2, 16.5, 18.6, and 20.9 kJ/g diet were included at various crude protein (CP) levels. Diets containing CP at 30, 40, 45, 50, and 55% had either 14.2 or 16.5 kJ/g energy; those with CP levels of 35, 40, 45, 50, and 60% had either 18.6 or 20.9 kJ/ g energy. After 2 wk of conditioning, fish initially averaging 7.3 ± 0.04 g (means ± SD) were randomly distributed into net cages as groups of 20 fish. Each diet was fed to fish in three randomly selected net cages for 8 wk.After 8 wk of the feeding trial, weight gain (WG) of fish fed 50% and 55% CP with 14.2 kJ/g diet was significantly higher than those of fish fed 30% and 40% CP diets (P 0.05). WG of fish fed 45, 50, and 55% CP with 16.5 kJ/g diet was significantly higher than those of fish fed 30% and 40% CP diets (P 〈 0.05). WG of fish fed 60% CP with 18.6 kJ/g diet was significantly higher than those of fish fed 35, 40, and 45% CP diets. WG of fish fed 45% CP with 20.9 kJ/g diet was significantly higher than those of fish fed 35, 40, and 60% CP diets. Generally, feed efficiency (FE) and specific growth rate (SGR) showed a similar trend as WG. However, protein efficiency ratio (PER) was negatively related to dietary protein levels. WG of fish did not always increase with increasing dietary protein and energy levels.Comprehensive comparison among diets containing 40, 45, and 50% CP with different energy levels indicated that the increase in protein from 40 to 45% significantly increased WG (P 〈 0.05), but such effect was not significant when protein increased from 45 to 50% at all energy levels. Increasing dietary energy significantly increased WG of fish fed 40% and 45% CP at each energy level; however, there was no difference in WG of fish fed 50% CP with energy levels of 18.6 and 2.9 kJ/g diet. There was no significant difference in WG of fish fed 50% CP with 18.6 kJ/g or 45 and 50% CP with 20.9 kJ/g diet.Broken-line analysis of weight gain indicated that the optimum dietary protein level was 50.9 ± 1.1% and PIE ratio was 35.4 ± 0.8 mg/kJ with 14.2 kJ/g diet; the optimum dietary protein level was 49.3 ± 5.0% and P/E ratio was 30.2 ± 1.0 mg/kJ with 16.5 kJ/g diet; the optimum dietary protein level was 46.2 ± 9.2% and P/E ratio was 24.7 ± 4.9 mg/kJ with 18.6 kJ/g diet; and the optimum dietary protein level was 45.1 ± 1.8% and P/E ratio was 21.5 ±0.7 with 20.9 kJ/g diet. Therefore, these data indicated that the concept of P/E ratio must be restricted to diets containing adequate protein and energy levels. Based on WG, the optimum P/E ratio was between 21.5 and 35.4 mg protein/kJ gross energy in juvenile Korean rockfish when gross energy ranged from 14.2 to 20.9 kJ/g diet.

Notes: A 6-wk feeding trial was conducted to reevaluate the phosphorus (P) requirement of juvenile olive flounder and the bioavailability of various inorganic phosphorus sources (IPS). Eight experimental diets were prepared such that all diets contained the same amount of calories, nitrogen, and calcium. Each diet included 0.33% total phosphorus (TP) and 0.60 % total calcium supplied by the basal diet. The eight experimental diets were: the basal diet without P supplementation (BD), three diets consisting of the BD supplemented with NaH,PO4.2H2O (NaP0.45 NaP0.57 or NaP1.14) to supply 0.45, 0.57 or 1.14% TP, and four diets consisting of the BD supplemented with K2HPO4 (KP0.57), Ca(H2PO4);H2O (Cap0.57), CaH2PO4;2H2O (CaHP0.57) or flounder bone meal (FBP0.57) to supply 0.57% TP. Fish (N = 480)averaging 4.02 ± 0.03 g (Mean ± SD) were distributed randomly into 24 aquaria (20 fish per aquarium), and were fed one of the eight experimental diets in triplicate groups.The weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER) and feed efficiency (FE) of fish fed the NaP0.57 diet were significantly higher than those of fish fed the BD, NaP1.14, KP0.57, CaHP0.57 and FBP0.57 diets (P 〉 0.05). There was no significant difference in WG, SGR, PER, and FER among fish fed the Nap0.45, NaP0.57 and Cap0.57, diets. Whole body P retention (WBPret) in fish fed the Nap0.57 diet was significantly higher than in fish fed the BD, NaP1.14, KP0.57 CaHP0.57 and FBP0.57diets (P 〉 0.05). There was no significant difference in WBPret among fish fed the NaP0.47, NaP0.57, and CaP0.57, diets. The ability of the fish to digest the phosphorus in the NaP0.45, Nap0.57, NaP1.14, and CaP0.57 diets was significantly better than that of fish fed the other diets (P 〉 0.05). These results indicated that the dietary P requirement for juvenile olive flounder could be 0.45457%. Also, NaH,PO; 2H2O and Ca(H2PO4);H2O appeared to have a better bioavailability than the other P sources in juvenile olive flounder.

Notes: The study was conducted to investigate the effects of dietary Chlorella powder (C) supplementation on growth performance, blood characteristics, and whole-body composition in juvenile Japanese flounder Paralichthys olivaceus. Four experimental diets were supplemented with C at 0, 1, 2 and 4% (C0, C1, C2, and C4) on a dry-weight basis. Three replicate groups of fish averaging 1.13 ± 0.02 g (Mean ± SD) were randomly distributed in each aquarium and fed one of four experimental diets for 12 wk. After 12 wk of the feeding trial, fish fed C2 diet had higher weight gain (WG), feed efficiency (FE), and protein efficiency ratio (PER) than did fish fed C0 and C1 diets (P 0.05); however, there was no significant difference among fish fed C1 and C4 diets, and among fish fed C2 and C4 diets (P 〉 0.05). Fish fed C2 and C4 diets had a lower serum cholesterol level than did fish fed C0 and C1 diets (P 0.05). Fish fed C2 and C4 diets had a lower body fat than did fish fed C0 (P 0.05). These results indicate that dietary supplementation of 2%Chlorella powder in the commercial diets could improve growth, feed utilization, serum cholesterol level, and whole-body fat contents in juvenile Japanese flounder.

Notes: An 8-week feeding trial was conducted to estimate the optimum dietary protein to energy (P/E) ratio in juvenile olive flounder Paralichthys olivaceus. Eight experimental diets were formulated with two energy levels and four protein levels at each energy level. Two energy levels of 12.5 and 16.7 kJ g−1 diets were included at crude protein (CP) levels of 25%, 30%, 35% and 45% with 12.5 kJ g−1, and CP levels of 35%, 45%, 50% and 60% with 16.7 kJ g−1. After 1 week of the conditioning period, fish initially averaging 8.1±0.08 g (mean±SD) were randomly distributed into the aquarium as groups of 15 fish. Each diet was fed on a dry-matter basis to fish in three randomly selected aquariums at a rate of 3–5% of total wet body weight per day for 8 weeks.After 8 weeks of the feeding trial, weight gain (WG), feed efficiency ratio and specific growth rate of fish fed 45% CP with 16.7 kJ g−1 energy diet were significantly higher than those from the other dietary treatments (P〈0.05). WG of fish fed 12.5 kJ g−1 energy diets increased with the increase of dietary protein levels. However, WG of fish fed 16.7 kJ g−1 energy diets increased with the increase of dietary protein levels up to 45% CP and then decreased when fish fed 50% and 60% CP diets. Both dietary protein and energy affected protein retention efficiency and energy retention efficiency. Haemoglobin (Hb) of fish fed 35% and 45% CP diets with 12.5 kJ g−1 energy were significantly high and not different from Hb of fish fed 45% and 50% CP diets with 16.7 kJ g−1 energy. Haematocrit of fish fed 45% CP diet with 16.7 kJ g−1 energy was significantly higher than those from fish fed 25% and 30% CP diets with 12.5 kJ g−1 energy (P〈 0.05). Based on the results of this experiment, we concluded that the optimum dietary P/E ratio was 27.5 mg protein kJ−1 with diet containing 45% CP and 16.7 kJ g−1 energy in juvenile olive flounder.

Notes: This experiment was conducted to study the effects of different dietary levels of vitamin C, L-ascorbyl-2-polyphosphate (ASPP), on growth and tissue vitamin C concentrations in juvenile olive flounder, Paralichthys olivaceus (Temminck et Schlegel). Fish were fed one of six semi-purified diets containing an equivalent of 0, 25, 50, 75, 150, or 1500 mg ascorbic acid (AA) kg−1 diet (C0, C25, C50, C75, C150 or C1500) in the form of ASPP for 12 weeks. Weight gain (WG) and protein efficiency ratio (PER) of fish fed the C0 diet were significantly lower than those of fish fed the other diets (P 〈 0.05), and WG and PER of fish fed the C25, C50 and C75 diets were significantly lower than those of fish fed the C1500 diet (P 〈 0.05). Fish fed the C0 diet exhibited vitamin C deficiency symptoms such as anorexia, scoliosis, cataract, exophthalmia and fin hemorrhage at the end of the 12-week test. After 12 weeks of the feeding trial, AA concentrations from gill, kidney, and liver of fish fed the C0, C25, C50 and C75 diets were significantly lower than those of fish fed the C150 and C1500 diets (P 〈 0.05). Based on broken line analyses for WG and PER, the optimum dietary levels of vitamin C were 91 and 93 mg AA kg−1 diet respectively. These findings suggest that the dietary vitamin C requirement could be 93 mg AA  kg−1 diet to support reasonable growth, and greater than 150 mg AA kg−1 diet may be required for AA saturation of major tissues for juvenile olive flounder under experimental conditions.

Notes: A long-term experiment was conducted in sea cages to compare three experimental extruded pellet (EP) diets with a raw fish moist pellet (MP) diet for Korean rockfish, Sebastes schlegeli (Hilgendorf). White fishmeal (WFM), soybean meal (SM) and fishmeal analogue (BAIFA-M™)-based experimental EP diets were formulated to be isonitrogenous and isocaloric with 50% crude protein (CP) with available energy of 16.7 kJ g−1 diet. An MP diet made of 80% frozen horse mackerel + 20% commercial binder meal was also included in the experiment. The proportions of the major protein ingredients in three experimental EP diets were as follows: WFM diet, 100% WFM; SM diet, 70% WFM + 30% SM; BAIFA-M™ diet, 70% WFM + 30% BAIFA-M™. The experiment was divided into three periods according to fish size: period I, initial weight of 20.2 ± 3.6 g (mean ± SD); period II, initial weight of 57.6 ± 4.7 g (mean ± SD); period III, initial weight of 96.3 ± 6.9 g (mean ± SD). There were no significant differences in weight gain, feed efficiency ratio, thermal-unit growth coefficient, specific growth rate, haemoglobin, or haematocrit among fish that were fed the four diets during all three periods. However, fish that were fed the MP diet had a lower survival rate than the fish that were fed the other three EP diets for all periods. These results strongly suggest that EP diets could be developed to replace MP diet for the grow-out stage of production of Korean rockfish without adverse effects on growth performance.

Notes: Two experiments were conducted to determine the optimum dietary inclusion level of dehulled soybean meal (DHSM) as a fish meal (FM) replacement in diets for olive flounder Paralichthys olivaceus. All the experimental diets were formulated to be isonitrogenous and isoenergetic to contain 50% crude protein (CP) and 16.7 kJ energy g−1 diet. In the first experiment, eight diets were formulated to replace FM with DHSM at 0%, 10%, 20% without amino acid (AA) supplementation; 20%, 30%, 40% with AA supplementation and 30%, 40% with AA & attractant supplementation (DHSM0, DHSM10, DHSM20, DHSM20+AA, DHSM30+AA, DHSM30+AA+Att, DHSM40+AA, DHSM40+AA+Att respectively). Triplicate groups of 25 fish averaging 5.0±0.04 g (mean±SD) were fed one of eight experimental diets for 8 weeks. In the second experiment, six diets were formulated to replace FM with DHSM at 0%, 10%, 20%, 30% without attractant supplementation and 20%, 30% with attractant supplementation (DHSM0, DHSM10, DHSM20, DHSM30, DHSM20+Att, DHSM30+Att respectively). Triplicate groups of 15 fish averaging 45.5±0.08 g (mean±SD) were fed one of six experimental diets for 10 weeks.Based on growth performance, we concluded that DHSM could replace FM up to 20% without AAs (lysine and methionine) and attractant supplementation, and up to 30% with AAs and/or attractant supplementation in diets for fingerling and growing olive flounder.