| Feeding trails were conducted to estimate dietary requirement of threonine,valine andhistidine for Japanese seabass(Lateolabrax japonicus) weighing about180g and330g/fish inseawater floating net cage (1.5m×1.5m×2.0m) for10weeks. Results of the study arepresented as follows:1. Six isonitrogenous and isoenergetic semipurified diets (42.25%crude protein,21.12KJ/ggross energy)were formulated with the graded supplemental levels of crystalline valine(0%,0.40%,0.80%,1.20%,1.60%,2.00%, respectively). The six experimental diets weredetermined to contain valine of1.12%,1.54%,1.96%,2.28%,2.54%and2.87%dry diet,respectively,and then used them to feed the six groups of Japanese seabass (averagebody weight:183.28±1.42g). The result showed the survival (85.18%-96.30%) were notaffected by dietary treatments significantly (P>0.05);With the increasing of dietary valinelevels,the specific growth rate (SGR),feed efficiency (FE) increased significantly(P<0.05), then these indexes showed a declining tendency after reaching the peaks at the1.96%dietary valine level;The dietary valine levels influence the protein productivevalue (PPV) and protein Efficiency Rate(PER) conspicuously;The activities ofglutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) inmuscle observably increased when valine level was increased from1.12%to1.96%(P<0.05), and then decreased when valine level was increased from1.96%to2.87%.Body composition was not significantly different from the fish fed different diets(P>0.05).Second-order regression analysis on the basis of specific growth rate (SGR)andfeed efficiency (FE) indicated that: the optimum dietary valine requirement was2.17%and2.14%of diet,respectively (5.14%and5.07%of dietary protein) for Japanese seabasswith initial averaged body weight (183.28±1.42)g.2. Six isonitrogenous and isoenergetic semipurified diets(42.00%crude protein,21.26KJ/ggross energy)were formulated with the graded supplemental levels of crystalline histidine(0%,0.05%,0.10%,0.15%,0.20%,0.25%, respectively). The six experimental dietswere determined to contain histidine of0.47%,0.50%,0.56%,0.60%,0.64%,0.68%dry diet, respectively,and then used them to feed the six groups of Japanese seabass(average body weight:174.19±1.48g). The result showed the survival (87.04%-90.74%)were not affected by dietary treatments significantly (P>0.05)；The SGR was better infish fed with0.56%histidine diet than those fed with other diet (P<0.05). With theincreasing of dietary histidine levels,feed efficiency (FE) increased significantly (P<0.05),then showed a declining tendency after reaching their peaks at the0.56%dietary histidine level, had the similar the activities of glutamic-oxaloacetic transaminase (GOT) andglutamic-pyruvic transaminase (GPT) in livers. Body composition was not significantlydifferent from the fish fed different diets (P>0.05). Second-order regression analysis onthe basis of specific growth rate (SGR) and feed efficiency (FE) indicated that: theoptimum dietary histidine requirement was0.57%of diet (1.36%of dietary protein) forJapanese seabass with initial averaged body weight (174.19±1.48)g.3. Six isonitrogenous and isoenergetic semipurified diets(46.17%crude protein,21.39%KJ/ggross energy)were formulated with the graded supplemental levels of crystalline histidine(0%,0.4%,0.8%,1.20%,1.60%,2.00%, respectively). The six experimental diets weredetermined to contain histidine of0.30%,0.46%,0.74%,1.02%,1.45%,1.85%dry diet,respectively,and then used them to feed the six groups of Japanese seabass (averagebody weight:341.58±7.27g). The result showed the survival (93.75%-100%) were notaffected by dietary treatments significantly (P>0.05)；The SGR was better in fish fed with0.74%histidine diet than those fed with0.30%,1.03%,1.45%,1.85%histidine diets(P<0.05),but there was no significant different with0.46%histidine diets. With theincreasing of dietary histidine levels, feed efficiency (FE) increased significantly(P<0.05), then these indexes showed a declining tendency after reaching their peaks atthe0.74%dietary histidine level, had the similar the activities of glutamic-oxaloacetictransaminase (GOT) and glutamic-pyruvic transaminase (GPT) in livers. Bodycomposition was not significantly different from the fish fed different diets (P>0.05).Regression analysis on the basis of specific growth rate (SGR) and feed efficiency (FE)indicated that: the optimum dietary histidine requirement was0.76%-0.78%of diet(1.65%-1.69%of dietary protein) for Japanese seabass with initial averaged body weight(341.58±7.27)g.4. Six isonitrogenous and isoenergetic semipurified diets (44.67%crude protein,21.65KJ/ggross energy) were formulated with the graded supplemental levels of crystallinethreonine(0%,0.35%,0.70%,1.05%,1.40%,1.75%, respectively). The diets weredetermined to contain threonine of1.05%,1.35%,1.65%,2.00%,2.42%and2.65%dry diet, respectively,and then used them to feed the six groups of Japanese seabass(average body weight:333.93±6.60g). The result showed the survival (89.58%-95.83%)were not affected by dietary treatments significantly (P>0.05). With the increasing ofdietary threonine levels, the specific growth rate (SGR) and feed efficiency (FE)increased significantly (P<0.05), then these indexes showed a declining tendency afterreaching their peaks at the2.00%dietary threonine level. Protein productive value (PPV)and Protein Efficiency Rate(PER) increased significantly (P<0.05) with the increase ofdietary threonine levels.The activities of glutamic-oxaloacetic transaminase (GOT) in livers observably increased when threonine level was increased from1.05%to2.00%(P<0.05), and then decreased when threonine level was increased from2.00%to2.65%.The highest activities of glutamic-pyruvic transaminase(GPT) in livers was obtained infish fed with2.00%of dietary threonine. Body composition was not significantlydifferent from the fish fed different diets (P>0.05). Second-order regression analysis onthe basis of specific growth rate (SGR)and feed efficiency (FE) indicated that: theoptimum dietary threonine requirement was1.84%and1.87%of diet,respectively(4.11%and4.18%of dietary protein) Japanese seabass with initial averaged body weight(333.93±6.60)g. |
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