饲料蛋白水平对斑节对虾生长、血液生化指标及体成分的影响

研究了蛋白含量为34%、38%和42%的3种饲料对斑节对虾(Penaeus monodon)血液生化指标和体成分组成的影响。实验结果表明,斑节对虾的特定生长率(S GR)在不同的饲料组中均有显著性差异(P0.05),特定生长率随着饲料蛋白水平的上升而上升;存活率(S R)在各饲料组中差异显著(P0.05),在38%蛋白水平饲料组中最高。斑节对虾血液中的谷丙转氨酶(GPT)、谷草转氨酶(GOT)两种酶的活性和总蛋白(TP)、白蛋白(ALB)的含量表现出随着蛋白水平的增加而上升的趋势,且在各饲料组中均有显著性差异(P0.05);血液中葡萄糖(GLUC)的含量也随着饲料蛋白水平的上升而上升,但上升的趋势不明显;血液中甘油三酯(TG)和胆固醇(CHOL)的含量在34%和38%蛋白水平饲料组中趋于一致,在42%蛋白水平饲料组中TG和CHOL的含量均有所上升,CHOL的上升趋势更为明显。随着饲料蛋白水平的增加,斑节对虾全虾蛋白质含量上升;水分含量下降,但下降趋势不明显(P0.05);灰分和脂肪的含量没有规律性的变化。     

蛋白水平对不同斑节对虾家系生长与消化酶活性的影响

为探究饲料蛋白水平与不同斑节对虾(Penaeus monodon)家系生长和消化酶之间的关系,研究了3种蛋白水平(34%、38%、42%)的饲料对16个斑节对虾家系的生长性状以及胃和肝脏消化酶活性的影响。经过56 d的养殖实验,结果表明:(1)随着蛋白水平的升高,所有斑节对虾家系的特定生长率均有所增加,F1、F2、F4、F7、F12、F13、F15等7个家系的特定生长率在34%、38%、42%3种蛋白水平组未见显著性差异(P>0.05),其余家系在3种或者其中的2种饲料之间有显著性差异(P<0.05);(2)斑节对虾特定生长率在家系和饲料蛋白质水平这两个因素间交互作用不显著(P=0.974);(3)所有斑节对虾家系的蛋白酶活性均随着饲料蛋白含量的增加而增加,淀粉酶活性有所下降,但规律不明显;(4)13个斑节对虾家系的肝脏蛋白酶活性、14个家系的胃蛋白酶活性均与家系特定生长率有着极显著的相关性(P<0.01),淀粉酶活性和特定生长率的相关性远小于蛋白酶活性。     

饲料蛋白水平对不同规格凡纳滨对虾蛋白质表观消化率和消化酶活性的影响

研究了7个蛋白质水平（32%、34%、36%、38%、40%、42%和44%）饲料对3个规格（Ⅰ：0.6-4.0 g;Ⅱ：4.0-10.0 g;Ⅲ：10.0-18.0 g）的凡纳滨对虾（Litopenaeus vannamei）蛋白质表观消化率、肝胰脏蛋白酶和淀粉酶活性的影响。规格Ⅰ对虾投喂36%的饲料组具有最大蛋白质表观消化率（85.61%）,规格Ⅱ和规格Ⅲ均在40%饲料组达到最大蛋白质表观消化率（分别为84.19%和84.67%）且显著高于其他组。规格Ⅰ40%饲料组具有最高的蛋白酶活力（26.67 U·mg-1）且显著高于44%饲料组,32%饲料组淀粉酶活力显著高于其他组,38%-44%饲料组淀粉酶活性无显著性差异;规格Ⅱ36%饲料组具有最高的蛋白酶活力（25.84 U·mg-1）,但各组之间差异不显著,32%-38%饲料组的淀粉酶活力显著高于40%-44%饲料组;规格Ⅲ44%饲料组蛋白酶活力显著高于32%饲料组,42%、44%饲料组淀粉酶活力均显著高于32%饲料组。     

凡纳滨幼虾采食不同蛋白水平日粮的免疫与消化率研究

在室内养殖条件下,进行单因素随机设计动物试验,即5种饲料蛋白质水平（31%、35%、39%、43%、47%;以A～E组表示）处理,投喂平均体质量0.2 g的凡纳滨幼虾,养殖60 d。研究结果表明,蛋白质营养对凡纳滨幼虾生长、免疫与抗氧化指标和消化率特征影响显著。随着饲料蛋白水平的升高,特定生长率显著增加,饲料系数下降,E组两项指标最好,分别为5.52和1.96。高蛋白质含量饲料有利于提高对虾免疫指标水平,血淋巴中血细胞浓度、T-AOC活力、POD活力、溶菌酶活力、总蛋白含量,随着蛋白质水平提高显著增加,各项指标E组最高,比A组分别显著提高133.7%、21%、16.8%、20.8%、19.7%(P<0.05);而SOD活力C组最高,与A组差异显著。凡纳滨幼虾对蛋白质的消化率随饲料蛋白质含量增加显著升高(P<0.05),E组比A组提高8.2%。通过饲料蛋白质水平与特定生长的回归分析,获得凡纳滨对虾幼虾最大生长饲料蛋白质需要量为46.5％。     

不同饲料能量源及其水平对凡纳滨对虾生长、抗氧化能力及蛋白质利用的影响

为探究不同饲料能量源及其水平对凡纳滨对虾(Litopenaeusvannamei)生长性能的影响,以饲料蛋白质含量为37%,蛋白能量比为20.23 mg/kJ的饲料作为对照组饲料(C),在此基础上分别通过提高饲料碳水化合物、脂肪含量调节饲料能量水平,制作饲料蛋白能量比分别为19.51 mg/kJ (中碳水化合物组, MC)、18.85 mg/kJ (高碳水化合物组, HC)、19.45 mg/kJ (中脂肪组, ML)和18.54 mg/kJ (高脂肪组, HL)的4组实验饲料,在淡水养殖条件下投喂初始体重为(0.6±0.02)g的凡纳滨对虾幼虾56d。结果表明,与对照组相比,提升饲料脂肪水平能显著提高凡纳滨对虾的生长性能和蛋白质沉积率(P<0.05),HL组凡纳滨对虾获得最大特定生长率及蛋白质沉积率;增加饲料碳水化合物水平对凡纳滨对虾的生长性能及蛋白质沉积率无显著影响(P>0.05)。与对照组相比, ML组、MC组、HC组对虾肌肉粗蛋白含量显著提高(P<0.05),HL组对虾肌肉粗蛋白含量较对照组有所提高,但差异不显著(P>0.05),对虾肌肉总脂肪含量则随着...     

不同蛋白水平饲料对斑节对虾家系生长及生长相关基因mRNA表达量的影响

研究了选育出的生长速度不同的9个斑节对虾(Penaeus monodon)家系在蛋白含量为34%、38%和42%饲料的饲喂下,其生长、生长激素基因(GH)、组织蛋白酶-L(Cathepsin-L)、胰蛋白酶(Trypsin)等基因的表达量及生长和基因表达量之间的相互关系。结果表明:1)斑节对虾的生长、3种基因的表达量与饲料中蛋白质含量均呈显著的正相关关系(P0.05);2)随着饲料蛋白质含量的增加,不同斑节对虾家系之间的生长差异和3种基因表达量的差异减小,相同斑节对虾家系在不同蛋白含量饲料的饲喂下,其特定生长率和基因表达量均具有显著性的差异(P0.05);3)选育的9个家系斑节对虾的生长在家系和蛋白质含量这两个因素间没有显著性的交互作用(P0.05),但是肝胰腺和肠道中3种基因的表达量在家系和蛋白质含量这两个因素间具有极显著的交互作用(P0.01),其中,饲料蛋白质含量因素对GH和Trypsin两个基因表达量的贡献率是家系因素的1.31~3.66倍,而饲料蛋白质含量因素对Cathepsin-L基因表达量的贡献率是家系因素的0.06~0.54倍。     

饲料蛋白质水平对红螯螯虾生长、消化酶和抗氧化系统的影响

为了探讨饲料不同蛋白质水平对红螯螯虾(Cherax quadricarinatus)生长及生理生化的影响,按照等能量不等蛋白的原则,配置蛋白质水平分别为20%、24%、28%、32%、36%、40%的6组饲料投喂初始体重为(0.35±0.07)g的红螯螯虾幼虾60 d,然后测定各相关指标。存活率随着饲料蛋白质水平的增加逐渐升高(P<0.05)。当饲料蛋白质水平为28%时,特定生长率、肥满度最高,饲料系数最低。饲料不同蛋白质水平对红螯螯虾胃中的蛋白酶活性影响显著(P<0.05),胃蛋白酶活力先升高后下降,32%组活性最大。肝胰腺中的淀粉酶、谷草转氨酶(GOT)、过氧化物歧化酶(SOD)活性变化不显著(P>0.05)。谷丙转氨酶(GPT)活性随着蛋白质水平的增加逐渐升高(P<0.05)。过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GPX)活性先升高后降低,腮Na+-K+ATP酶则相反(P<0.05)。36%组和40%组的丙二醛(MDA)含量最高,其次为20%组,均显著高于其他各组(P<0.05)。结果表明红螯螯虾对饲料蛋白质含量的要求较低,28%即可满足其要求。豆粕含量过高可能会影响其生长。     

3种蛋白水平饲料对克氏螯虾生长和虾肉品质的影响

采用40%、33%、27%3种蛋白水平的配合饲料和纯菜粕(对照组)分别投喂克氏螯虾(Procambarus clar-kii)98 d,研究不同蛋白水平的饲料对克氏螯虾生长和肉质的影响。结果显示:克氏螯虾增重以27%组最高,其次是40%组、33%组,对照组最低;克氏螯虾体长增长以27%蛋白组最高,其次是33%、40%组,对照组最低;饲料系数以33%组最低,其次是27%组、40%组,对照组最高。随着饲料蛋白质含量升高,蛋白质效率呈下降的趋势。27%组出肉率、虾黄率含量最高;滴水损失40%组显著高于27%组(P<0.05);蒸煮损失27%组(P<0.01)、33%组(P<0.05)组均显著低于对照组;不同蛋白水平组间的虾肉水分含量、肉样pH值(pH1和pH2)、熟肉率、嫩度没有显著差异。试验表明克氏螯虾饲料中蛋白质水平以27%和33%比较适合。     

草金鱼幼鱼蛋白质需要量的初步研究

分别给初始体重为(19.56±1.78)g的金鱼幼鱼投喂蛋白质水平为26%、28%、30%、32%、36%、40%和42%的7种颗粒饲料,探讨草金鱼对饲料中蛋白质的需求。38d饲养试验结果表明:饲料中蛋白质含量36%时,草金鱼的增重率最大,显著高于蛋白质含量为26%、28%、30%和42%的饲料组(P<0.05),蛋白质含量为32%～40%的3个组间的增重率没有明显差异(P>0.05)。蛋白质含量为28%～44%饲料组的蛋白质效率无显著差异(P>0.05)。蛋白质含量为36%的饲料组饲料系数最低。通过对相对增重率和蛋白质效率两项指标的回归分析,确定草金鱼幼鱼配合饲料最适蛋白质含量为33.83%～35.31%。     

饲料中蛋白质水平对克氏原螯虾生长性能及肌肉品质的影响

以初始平均体质量为(3.69±0.05)g的克氏原螯虾幼虾为研究对象,配制蛋白质水平分别为27.72%、30.09%、33.05%、35.31%和37.57%的5种等能、等脂的配合饲料,进行为期47 d的饲养试验,探索饲料中不同蛋白质水平对克氏原螯虾生长性能、肌肉质构特性、常规营养成分及氨基酸组成和含量的影响。结果表明:随着饲料蛋白质水平的增加,克氏原螯虾的增重率和特定生长率呈先上升后降低的趋势,其中饲料蛋白质水平为30.09%组虾的增重率、特定生长率显著高于其他各组(P<0.05);各组间饲料系数、虾体质量/体长比、肝体指数、得肉率以及成活率无差异统计学意义(P>0.05)。饲料蛋白质水平为27.72%组虾的肌肉硬度、咀嚼性显著高于饲料蛋白质水平为35.31%、37.57%组(P<0.05),饲料蛋白质水平为30.09%、33.05%组虾的肌肉弹性显著高于饲料蛋白质水平最低组(P<0.05),饲料蛋白质水平最高组虾的回复性显著低于其他各组(P<0.05),各组间虾肌肉内聚力无差异统计学意义(P>0.05)。随着饲料蛋白质水平的增加,克氏原螯虾的肌肉粗蛋白含量呈先升高后趋于稳定的变化趋势,饲料蛋白质水平为35.31%、37.57%组虾的肌肉粗蛋白含量显著高于饲料蛋白质水平最低组(P<0.05);各组间虾的肌肉水分、粗脂肪、灰分含量差异不具统计学意义(P>0.05)。肌肉总氨基酸、总必需氨基酸、总非必需氨基酸以及亮氨酸、赖氨酸、天门冬氨酸、谷氨酸随饲料蛋白的升高均呈先升高后趋于稳定的变化趋势。综合考虑生长性能、肌肉品质以及成本效益,建议克氏原螯虾饲料蛋白质水平为30.09%。     

Reevaluation of the Dietary Protein Requirement of Japanese Flounder Paralichthys olivaceus

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.     

Growth,feed utilization and body composition of African bonytongue,Heterotis niloticus,fingerlings fed diets containing various protein and lipid levels

In order to evaluate the effects of dietary protein and lipid levels on the growth, feed utilization and body composition of Heterotis niloticus fingerlings, a factorial experiment with three replicates was conducted. Six experimental diets containing three crude protein levels (28%, 32% and 36%) and two crude lipid levels (6% and 13%) were tested. Heterotis niloticus (2.34 g) were fed with the diets to apparent satiation, twice a day. For 56 days, weight gain (WG), specific growth rate (SGR), feed efficiency (FE) and protein retention (PR) were significantly affected by dietary protein and dietary lipid levels respectively (P<0.01). The highest WG, SGR and FE were observed for fingerlings fed the diet containing 36% protein and 6% lipid, but no significance difference was found between groups fed with the following diets: P28L13 (28% protein and 13% lipid), P32L6, P32L13 and P36L13. A significant interaction between dietary protein and lipid was observed for WG, SGR, FE and PR. The whole‐body protein, lipid, moisture and ash content were not significantly affected by dietary lipid levels, but body protein and lipid content were significantly affected by dietary protein. The dietary protein‐sparing effect was clearly demonstrated when the dietary energy of lipid increased from 17 to 19.6 kJ g^?1 at 28% crude protein on H. niloticus.     

Comparison of L‐lysine·HCl and L‐lysine sulphate in the feed of Penaeus monodon and re‐evaluation of dietary lysine requirement for P. monodon

Two trials were conducted to compare L‐lysine HCl and L‐lysine sulphate regarding its availability to Penaeus monodon, and further evaluate the optimum dietary lysine requirement. In experiment 1, five experimental diets were formulated (D1, D2, D3, D4 and D5), a basal diet (D1), aimed at a low‐lysine concentration (2.22% dry matter), with lysine concentration of the other four diets increasing in two 0.25% L‐lysine intervals from either L‐lysine HCl (D2 and D3) or L‐lysine sulphate (D4 and D5). Each diet was fed at a restricted rate to three groups of 40 shrimp for 74 days. The highest values of growth performance (weight gain, WG; specific growth rate, SGR) and survival were observed with shrimp fed the L‐lysine HCl diet. Feed efficiency (FE) of shrimp fed D2 was significantly higher than that of shrimp fed D1 and D5 (P < 0.05), but without significant difference with shrimp fed D3 and D4 (P > 0.05). In experiment 2, six diets (d1, d2, d3, d4, d5 and d6) were formulated with six graded levels of lysine (2.21%, 2.41%, 2.59%, 2.87%, 3.11% and 3.29% of diet). Each diet was randomly assigned to triplicate groups of 40 shrimp for 74 days. WG, SGR and survival increased increasing levels of lysine up to 2.41% of diet and reached an apparent plateau. Broken‐line model analysis on WG and SGR indicated that the optimum dietary lysine level for optimal growth of shrimp was 2.37% of diet, corresponding to 5.78% of dietary protein. In conclusion, results of this trial suggest that L‐lysine HCl is superior to L‐lysine sulphate when fed to Penaeus monodon and optimal growth can be obtained at lysine levels corresponding to 2.37% of diet, or 5.78% of dietary protein in this specie.     

Effects of dietary protein levels on the growth,survival, amylase and trypsin activities in large yellow croaker,Pseudosciaena Crocea R., larvae

A feeding trial was conducted to investigate the effects of dietary graded protein levels on the growth, survival, amylase and trypsin activities of large yellow croaker (Pseudosciaena crocea R.) larvae from 12 to 42 days after hatching (DAH). Five approximately isoenergetic microbound diets (16.65 MJ/kg diet) were formulated to contain different protein (47.1%, 52.0%, 57.1%, 62.2% and 67.5%) levels. Frozen copepods, containing 54.5% crude protein (CP), 6.0% crude lipid, 27.2% ash and 6.7% glycogen, were used as a control. Each diet was randomly fed to triplicate groups of larvae with an initial mean body weight of 1.76 ± 0.09 mg (mean ± SD) in 180 L white plastic tanks, and each tank was stocked initially with 3500 larvae. Both the survival and the specific growth rate (SGR) of large yellow croaker larvae significantly increased with increasing dietary protein level up to 57.1%, and decreased thereafter. Frozen copepods resulted in intermediate survival and low SGR compared with the other diets. Whole‐body moisture and protein of larvae were not significantly affected by the dietary protein level. In contrast, whole‐body lipid of larvae fed diet with 47.1% CP was significantly higher (P<0.05) than those from fish fed the diets containing more than 57.1% CP. Additionally, fish fed the frozen copepods had the lowest whole‐body protein and lipid. The amylase‐specific activity increased with increasing dietary carbohydrate level during the period of this experiment. However, trypsin activity was not significantly affected by the dietary protein content before 42 DAH, indicating a later onset of trypsin than amylase in the regulation of enzymatic synthesis induced by a dietary substrate.     

Dietary thiamin could improve growth performance,feed utilization and non‐specific immune response for juvenile Pacific white shrimp (Litopenaeus vannamei)

This study evaluated the effect of dietary thiamin on growth performance, feed utilization and non‐specific immune response for juvenile Pacific white shrimp, Litopenaeus vannamei. Six isonitrogenous and isolipidic practical diets were formulated with graded thiamin levels of 6.9, 32.7, 54.2, 78.1, 145.1 and 301.5 mg kg^?1 of dry diet, respectively. Each diet was randomly assigned to triplicate groups of 30 juvenile shrimp and provided four times each day to apparent satiation. Weight gain (WG) and specific growth rate (SGR) of the shrimp were significantly influenced by the dietary thiamin levels, the maximal WG and SGR occurred at 54.2 mg kg^?1 dietary thiamin level. However, with further increase in dietary thiamin level from 54.2 to 301.5 mg kg^?1, the WG and SGR significantly decreased. Shrimp fed the 54.2 mg kg^?1 thiamin diet exhibited higher feed efficiency, protein efficiency ratio and protein productive value than those fed the other diets. Dry matter and protein content in whole body were significantly affected by the dietary thiamin levels. Thiamin concentration in hepatopancreas significantly increased when the dietary thiamin level increased from 6.9 to 145.1 mg kg^?1. The total protein, glucose, triacylglycerol and cholesterol contents in hemolymph were not significantly affected by the dietary thiamin levels. Dietary thiamin had significantly influenced superoxide dismutase, catalase and lysozyme activities in hemolymph. Results of this study indicated that the optimal dietary thiamin requirements estimated using a two‐slope broken‐line model based on WG and thiamin concentration in hepatopancreas were 44.66 and 152.83 mg kg^?1, respectively.     

饲料蛋白水平对方格星虫稚虫日增重和消化酶活性的影响

为探讨饲料蛋白水平对方格星虫稚虫日增重和消化酶活性的影响,以9种蛋白水平(25.21%、29.87%、35.03%、40.67%、45.47%、50.12%、55.29%、60.38%、64.85%)的等能微颗粒饲料(以D1-D9表示)饲喂稚星虫8周。结果表明,饲料蛋白水平对稚星虫的日增重有显著影响(P<0.05)。随着饲料蛋白水平的提高,稚星虫的日增重呈先增后降的趋势,在D5组达到最大值。对稚星虫消化酶活性的分析表明,稚星虫蛋白酶活性随着饲料蛋白水平的上升呈先增后降的趋势,在D6组达到最大值,且显著高于D1-D5组(P<0.05);淀粉酶和脂肪酶活性随着饲料蛋白水平的上升有显著降低的趋势(P<0.05),D9组稚星虫的淀粉酶活性显著低于D1-D4组(P<0.05);D9组稚星虫脂肪酶活性显著低于除D8组外的其他各蛋白水平组(P<0.05)。以日增重为评价指标,稚星虫对饲料蛋白的适宜需求量为46.69%。     

Effect of dietary carbohydrate level on growth performance,body composition,apparent digestibility coefficient and digestive enzyme activities of juvenile cobia,Rachycentron canadum L

A 9‐week feeding trial was conducted to investigate the effect of dietary carbohydrate level on the growth performance, body composition and apparent digestibility coefficient and digestive enzyme activities of juvenile cobia. Six isonitrogenous and isolipidic diets containing graded levels of starch (1.3%, 6.5%, 12.5%, 18.4%, 24.2% and 30.4%) were fed to juvenile cobia. Specific growth rate (SGR), feed efficiency ratio (FER) and protein efficiency ratio (PER) increased with increasing dietary starch up to 18.4% (P<0.05), and thereafter SGR declined but FER and PER remained nearly the same. Apparent digestibility coefficient of starch reduced significantly when dietary starch up to 30.4%. Fish fed the diets with starch from 18.4% to 30.4% showed higher amylase activities in intestinal tract than those fed diets containing starch 1.3% and 6.5% (P<0.05). Significantly higher whole‐body lipid contents were observed in fish fed the diets containing higher starch. Whole‐body moisture content was inversely correlated with whole‐body lipid content, while protein and ash showed no significant differences. Plasma glucose, hepatosomatic index, liver glycogen and liver lipid increased with an increasing dietary starch. Based on SGR and FER, the appropriate dietary starch supplementations of juvenile cobia were estimated to be 21.1% and 18.0 % of diet respectively.     

Optimum Dietary Protein Level and Protein‐to‐energy Ratio for Growth of Juvenile Parrot Fish,Oplegnathus fasciatus

An 8‐wk feeding trial was conducted to estimate the optimum dietary protein level and protein‐to‐energy (P/E) ratio in juvenile parrot fish, Oplegnathus fasciatus. Eight experimental diets were formulated with two energy levels and four protein levels for each energy level. Diets containing crude protein (CP) at 35, 40, 45, and 50% had either 12.5 or 14.6 kJ/g of energy. Fish averaging 7.1 ± 0.06 g (mean ± SD) were fed one of the experimental diets for 8 wk. At the end of the feeding trial, weight gain (WG) of fish fed 45 and 50% CP in the 12.5 kJ/g diet was significantly higher than fish fed the 35% CP diet (P < 0.05). WG of the fish fed 45 and 50% CP in the 14.6 kJ/g diet was significantly higher than fish fed the 35 and 40% CP diets (P < 0.05). Fish fed the 14.6 kJ/g diet had a higher WG compared with fish fed the 12.5 kJ/g diet at all CP levels. Feed efficiency (FE) and specific growth rate (SGR) showed a similar trend to the WG. WG, FE, and SGR improved with increasing dietary protein levels up to 45% and remained constant at 50% CP for both energy levels. However, protein efficiency ratio was negatively related to dietary protein levels. The results suggested that the optimum level of protein and the optimum P/E ratio for juvenile parrot fish should be 45% and 31.1 mg protein/kJ, respectively, in a diet containing 14.6 kJ/g energy.