梭鲈幼鱼摄食与生长的初步观察

食性转换期的梭鲈（体长２—３ｃｍ），除摄食活鱼外，通过人工驯食还可以摄取鱼肉和人工配合饵料。其体长—时间回归方程为：Ｌ＝０１７５＋００８８ｔ－１１７１×１０－４ｔ２（ｔ：３９—３１５天），体重一体长回归方程为：Ｗ＝００２１９Ｌ２．６８１０，鱼体三维形态类似黄颡鱼     

饲料中不同脂肪源对黑鲷幼鱼生长和鱼体脂肪酸组成的影响

用相同比例,不同种类的脂肪源配制成４组试验饲料,对黑鲷幼鱼进行了４５ｄ的饲养试验。结果表明,以大豆油,鱼油为饲料脂肪源的试验组的幼鱼增重率较高,分别为３４．８＊１０＾－２和２９．３＊１０＾－２。花生油组和猪油组的幼鱼增重率分别为２５．４＊１０＾－２和２５．５＊１０＾－２,饲料转换系数分别为鱼油组１．０８,豆油组１．２１,花生油组１．３５和猪油组１．５９。从试验饲料和鱼体脂质的脂肪酸分析结果表明,鱼     

不同脂肪源饲料对施氏鲟幼鱼生长的影响

在饲料蛋白质水平和能量水平均能满足生长需要的前提下，以不同的油脂配制成6种试验饲料，投喂施氏鲟幼鱼7周，综合分析其生长效率各参数。试验结果表明：混合油组的总体生长效果最好，而葵花籽油和猪油组最差。分析表明：除了ω3多不饱和脂肪酸(PUFA)之外，施氏鲟的必需脂肪酸还同时包括18：2ω6，且施氏鲟对18：3ω3的需求要比18：2ω6大；另外，鱼油氧化后对施氏鲟幼鱼生长也有显著影响。     

饲料脂肪水平对江黄颡鱼幼鱼生长性能的影响

研究了饲料中脂肪水平对江黄颡鱼幼鱼(平均体重0.44g)生长性能的影响。实验共设5个水平组,饲料脂肪水平分别为3.77%,4.82%,7.29%,8.37%,9.87%。每组20尾,3个平行,饲养66d。结果显示:随着饲料脂肪水平的升高,江黄颡鱼幼鱼的饲料系数呈上升趋势,蛋白质效率则呈下降趋势,增重率和特定生长率呈抛物线变化,但饲料系数和蛋白质效率差异不显著(P0.05),增重率和特定生长率差异显著(P0.05)。江黄颡鱼幼鱼肝脏中脂肪的蓄积量随饲料中脂肪水平的增加而增加。综合各项指标并分析增重率、特定生长率与脂肪水平的回归性关系,可以推测江黄颡鱼幼鱼期的饲料脂肪水平应该维持在7.59%~7.65%。     

饵料蛋白能量比对黑鲷幼鱼生长和体成分的影响

取黑鲷(Sparusmacrocephalus)幼鱼960尾,体重(3.39±0.18)g,以鱼粉和豆粕作为蛋白源,鱼油和豆油等比例混合油作为脂肪源,共配制4个蛋白水平(34%、38%、42%、46%),每一蛋白水平设3个脂肪水平(10%、13%、16%),共12种饵料,糖水平保持在16%左右,饵料的蛋白能量比(P/E)在96.76～136.21mg/kcal。黑鲷幼鱼随机分成12组,每组设2重复,实验为期42d。结果表明,对特定生长率(SGR)与饵料系数(FCR)的影响,以较高蛋白组(38%、42%、46%)显著优于低蛋白组(34%)(P<0.05),中、高脂肪组(13%、16%)显著优于低脂肪组(10%)(P<0.05);各组饵料对成活率的影响无显著差异(P>0.05)。当蛋白水平为42%,脂肪水平为16%时,黑鲷幼鱼获得最大特定生长率(3.20)、最高蛋白质效率(2.10)和最小饵料系数(1.14)。全鱼脂肪含量随着饵料中脂肪水平的提高而逐渐升高。在同一饵料蛋白水平内,全鱼蛋白与灰分含量随着饵料脂肪水平的提高呈逐渐升高趋势。经统计分析,饵料中不同蛋白能量比显著影响黑鲷幼鱼生长(P<0.05),饵料中脂肪有明显节约蛋白质的作用(P<0.05)。由生长及体成分的实验结果得出,黑鲷幼鱼的最适饵料蛋白水平为42%,最适蛋白能量比(P/E)为110.37mg/kcal。     

不同蛋白能量比饲料对草鱼幼鱼消化酶活性的影响

以鱼粉和豆粕为蛋白源,鱼油和豆油等比例混合油为脂肪源,共配制4个蛋白水平(20%、25%、30%、35%),每一蛋白水平设4个脂肪水平(4.5%、8%、11.5%、15%),共16组饲料。每组设3个重复,在水温23~29℃下,连续投喂初始体重为(16.84±0.28)g的草鱼(Ctenopharyngodon idellus)10周,研究不同蛋白能量比饲料对草鱼幼鱼消化酶活性的影响。结果显示:肠道蛋白酶的活性随着饲料蛋白含量的升高而显著升高(P<0.05),饲料蛋白水平在20%~30%时,饲料中的脂肪水平对蛋白酶活性影响不显著(P>0.05),蛋白水平在35%时,高脂肪抑制了蛋白酶活性,肝胰脏的蛋白酶变化规律类似于肠道;肠道和肝胰脏淀粉酶活性在饲料蛋白含量相同的情况下,随着脂肪含量的升高呈现显著的下降趋势(P<0.05),但饲料中蛋白(30%,35%)和脂肪(8%,11.5%,15%)含量较高时,淀粉酶活性较稳定;肠道和肝胰脏的脂肪酶活性在饲料蛋白含量相同的情况下,随着脂肪含量的升高,呈显著上升的趋势(P<0.05),但在蛋白含量(30%,35%)和脂肪含量(8%、11.5%,15%)的6个试验组之间差异不显著(P>0.05);在脂肪含量分别为4.5%、8%和11.5%时,饲料的蛋白含量对肠道的脂肪酶活性无显著性影响(P>0.05),当脂肪含量为15%时,随着蛋白含量的升高,肠道的脂肪酶活性显著降低(P<0.05)。结果表明,草鱼饲料中蛋白含量为30%和脂肪为8%(即蛋白能量比21.7 mg/kJ)的试验组草鱼获得较高的消化酶活性。     

不同饲料蛋白水平对华鲮幼鱼生长的影响

用3种不同蛋白含量（26．1％、38．3％、52．7％）的配合饲料投喂华鲮幼鱼153d，随着饲料蛋白质含量从26．1％上升到52．7％，平均日增重从0．08g／d上升到0．33g／d，3组之间的日增重和体重有显著差异（P〈0．05）；饲料系数从4．82下降为2．18，3组之间的饲料系数有显著差异（P〈0．05）。3种不同蛋白含量（26．1％、38．3％、52．7％）的配合饲料的成本分别为2．53元／kg、3．75元／kg、5．57元／kg；鱼体每kg增重所需饲料成本分别为12．19元、10．39元、12，14元／。初步认为蛋白含量为38．3％的配合饲料更适合华鲮幼鱼的生产需要。     

卵形鲳鲹幼鱼饲料中适宜蛋白能量比的研究

以鱼粉、豆粕为蛋白源,豆油、鱼油为脂肪源,配制9种不同蛋白能量水平的饲料,蛋白质3个水平(38%、43%、49%),每个蛋白水平设3个脂肪梯度(6%、10%、14%),其蛋白能量比为19.3～27.4mg/kJ。卵形鲳鲹初始质量为(25.02±0.16)g,每个处理设3个重复,每个网箱(1.5 m×1.0 m×2.0m)放养卵形鲳鲹苗20尾,养殖试验持续8周。结果显示,卵形鲳鲹特定生长率随饲料蛋白水平的升高而显著升高(P<0.05)。投喂含43%或49%蛋白质、6%脂肪饲料的卵形鲳鲹表现出较好的特定生长率。饲料中不同的脂肪水平未表现出蛋白质节约效应,较高的脂肪水平反而抑制了卵形鲳鲹的特定生长率、饲料效率和蛋白质效率。卵形鲳鲹鱼体蛋白和脂肪含量分别随饲料蛋白质和脂肪水平的上升而显著升高(P<0.05)。在该试验条件下,卵形鲳鲹幼鱼饲料中最适蛋白质、脂肪水平和蛋白能量比分别为43%、6%和24.4 mg/kJ。     

日本沼虾饲料最适蛋白质、脂肪含量及能量蛋白比的研究

本文研究了日本沼虾(Macrobrachium nipponense)饲料的最适蛋白质含量、脂肪含量及能量蛋白比。试验用饲料由酪蛋白、糊精、混合油、复合维生素和无机盐混合物等组成。本试验用的日本沼虾体重为 1.77±0.23克,试验期间水温为 21—25℃。用增重率、饲料系数和肝胰脏α-淀粉酶活力等作为评价指标。试验结果表明:日本沼虾配合饲料适宜蛋白质含量为 36.8—42.27％,适宜脂肪含量为6—12％。当配合饲料的蛋内质含量在适宜范围内,饲料能量蛋白比(C/P)为8千卡/克蛋白左右,每公斤配合饲料的总能量为3006—3561千卡是最为适宜的。当饲料总能量在一定范围内,随着饲料碳水化合物含量的增加,肝胰脏α-淀粉酶活力增强。     

团头鲂两个生长阶段适宜蛋白/脂肪比的需要量

为了在相同配方体系下研究团头鲂两个生长阶段对饲料中蛋白/脂肪比的需要量,以初均重为(35.07±0.45)g(幼鱼)、(101.65±1.82)g(育成鱼)两个阶段的团头鲂为实验鱼,以秘鲁鱼粉、酪蛋白、大豆磷脂、豆油等原料配制半纯化饲料,在蛋白质26.93%~35.63%、脂肪10.24%~3.35%范围内,设置蛋白/脂肪比浓度分别为2.63、3.20、4.07、5.33、7.25和10.64共6组饲料。分别在池塘网箱养殖85和56 d,每组实验鱼设置4个平行。结果发现,随着饲料蛋白/脂肪比水平的增加,两个阶段的团头鲂体质量特定生长率(SGR)、蛋白质沉积率(PDR)、能量保留率(ERR)总体均呈现先上升后下降的趋势,均在饲料蛋白/脂肪比为5.33组达到最高;饲料系数(FCR)则呈先下降后上升的趋势,且均在饲料蛋白/脂肪比为5.33组达到最低。分别以实验鱼特定生长率(SGR)、饲料系数(FCR)、蛋白质沉积率(PDR)及能量保留率(ERR)作为评价指标,经过回归分析可知,幼鱼阶段团头鲂对饲料中蛋白/脂肪比需要量为6.09~7.58,适宜蛋白质水平为32.83%~33.98%、脂肪水平为4.48%~5.39%;在日均摄食量为5.06 g/100 g体质量的条件下,团头鲂幼鱼对饲料蛋白质每日需要量为1.66~1.72 g/100 g体质量,对饲料脂肪每日需要量为0.23~0.27 g/100 g体质量。育成鱼阶段团头鲂对饲料中蛋白/脂肪比需要量为4.03~4.34,适宜蛋白质水平为30.19%~30.72%、脂肪水平为7.07%~7.49%。在日均摄食量为3.61 g/100 g体质量的条件下,团头鲂育成鱼对饲料蛋白质每日需要量为1.09~1.11 g/100 g体质量,对饲料脂肪每日需要量为0.26~0.27 g/100 g体质量。     

饲料中蛋白脂肪比对斑点叉尾鮰幼鱼生长、消化酶活性及肌肉成分的影响

探讨了不同的蛋白和脂肪水平对斑点叉尾生长与品质等的影响,试验设计以豆粕调节蛋白含量,混合油脂(鱼油∶豆油=1∶1)调节脂肪含量,并以α-淀粉和次粉为填充物,共配制3个蛋白(P)水平(28%,32%,36%),每一蛋白水平设3个脂肪(L)水平(5.0%,7.5%,10.0%),共9种饲料,分别为P28L10,P32L10,P36L10,P28L7.5,P32L7.5,P36L7.5,P28L5,P32L5和P36L5,每组4重复,每重复80尾鱼[(1.5±0.02)g]。饲养60d后,进行生产性能测定,并采集肌肉等组织样本,测定相关指标。结果表明:饲料蛋白脂肪比对斑点叉尾幼鱼生长有显著影响(P<0.05)。其中P36L7.5组增重率(WGR)、饲料效率(FCR)最高,与P36L10和P32L7.5组差异不显著(P>0.05),但显著高于其它组(P<0.05)。P36L10组试验鱼肥满度(CF)最高,与P32L7.5和P36L7.5组差异不显著(P>0.05),但显著高于其他组(P<0.05)。鱼体内脏比(VBR)、腹脂率(MSI)随脂肪水平降低而显著降低(P<0.05)。试验各组肌肉水分含量差异不显著(P>...     

Optimum dietary protein to lipid ratio for Starry flounder (Platichthys stellatus)

An 8‐week feeding trial was conducted to evaluate the optimum dietary protein to lipid ratio (P/L) for Starry flounder Platichthys stellatus (30.7 ± 0.7 g initial weight). Nine fishmeal‐based diets with three protein levels (40%, 45% and 50%) and three lipid levels (8%, 11% and 14%) were fed to 30 fish in triplicate. Results showed that the growth performance was affected by dietary P/L ratio significantly, and the best weight gain rate, specific growth rate and feed conversion ratio were appeared at fish fed P45L14 and P50L11 diets. Apparent digestibility coefficient of protein was increased with increasing dietary lipid, but lipid digestibility was decreased by dietary lipid. Lipid deposition in tissues was increased with increasing dietary lipid at each protein level and was higher for the lower protein diets. In liver, the per cent of both eicosapentaenoic acid and docosahexaenoic acid were increased by dietary protein. High dietary protein level (50%) at high lipid level (14%) increased arachidonic acid significantly. Aspartate aminotransferase and alanine aminotransferase were affected significantly by dietary P/L ratios. High density lipoprotein cholesterol and total cholesterol of 45% protein groups were significantly higher than others. The study revealed that the optimum dietary protein to lipid ratio for starry flounder was P45L14 or P50L11, or P/E ratios were 25.49 and 27.70 mg protein kJ^?1 gross energy respectively.     

Effects of varying dietary protein to lipid ratios on growth performance and body composition of juvenile pike perch (Sander lucioperca)

The present study investigated the effect of varying dietary protein‐to‐lipid ratios (P/L) on growth performance and body composition of pike perch (Sander lucioperca) fingerlings with an initial body weight of 1.35–1.40 g. Triplicate groups were reared during 56 days in recirculation systems and fed six experimental diets containing three dietary levels of lipid (90, 130, 170 g kg^?1 of dry matter, d.m.) combined with two levels of dietary protein (470, 540 g kg^?1 d.m.). During the experimental period the fixed feeding rates decreased from 10% to 5% of the total fish biomass per day. In contrast to previous results obtained with this species, the present study clearly demonstrated the occurrence of protein sparing effect. The best results for feed conversation ratio and specific growth rates were obtained in the treatments containing highest lipid level: diet 3 (P/L 47/17) and diet 6 (P/L 53/17). The d.m. and crude lipid contents of pike perch whole body increased in direct proportion of the dietary lipid levels. No difference was observed on crude protein and ash content among the treatments. Increasing hepatosomatic index at highest dietary lipid level suggested a limited lipid utilization of percids.     

饲料蛋白质和脂肪水平对牛蛙生长性能的影响

为研究饲料中不同蛋白质和脂肪水平对牛蛙生长、体组成和肝脏健康的影响,以红鱼粉、豆粕和酪蛋白为蛋白源,鱼油和豆油为主要脂肪源,α-淀粉为主要糖源,微晶纤维素为填充剂,并补充无机盐和维生素等配制实验饲料。实验设3个蛋白水平(35%、40%和45%),每个蛋白水平下设4个脂肪水平(4%、7%、10%和13%),共12种饲料,饲料可利用能变化范围为12.4~17.8 kJ/g,蛋白能量比变化范围为21.9~32.0 mg/kJ。每种饲料设置3个重复,每个水族缸放养12只牛蛙[初始平均体质量为(91.5±1.1)g],每日饱食投喂2次,实验周期56 d。结果发现,饲料蛋白质和脂肪水平对牛蛙的存活率无显著影响,而13%脂肪组的牛蛙肝脏出现颜色不均一和肝体脆化无韧性的现象。饲料蛋白质和脂肪水平显著影响牛蛙的增重率、特定生长率、摄食率、饲料效率和蛋白质效率。其中,40%蛋白组牛蛙的增重率和特定生长率显著高于35%蛋白组,与45%蛋白组无显著差异。随着蛋白质水平的升高,饲料效率显著升高,而摄食率和蛋白质效率显著降低。随着脂肪水平的升高,增重率、特定生长率和摄食率显著升高,饲料效率、蛋白质效率和氮保留率无显著差异。饲料脂肪水平与牛蛙全体的脂肪含量和总能水平正相关,但不影响牛蛙全体的蛋白质含量。随着饲料脂肪水平的升高,牛蛙肝脏丙二醛含量显著升高,过氧化氢酶和脂蛋白酯酶活力先升高后降低。研究表明,牛蛙饲料适宜的蛋白质和脂肪水平分别为40%和7%,适宜蛋白能量比为27.7 mg/kJ。     

Optimum dietary protein and lipid levels for juvenile rockfish (Sebastes schlegeli,Hilgendorf 1880)

Optimum dietary protein and lipid levels for juvenile rockfish were determined. Eight hundred and ten juvenile fish averaging 3.22 g were randomly chosen and distributed into 27 flow‐through tanks of 50 L (30 fish per tank). Nine experimental diets were prepared according to a 3 × 3 factorial experimental design: three crude protein levels (45%, 50% and 55%) × three crude lipid levels (11%, 15% and 19%). Crude protein and crude lipid levels increased at the expense of dextrin and cellulose in the experimental diets. Survival of fish was not affected by either dietary protein or lipid level. Weight gain of fish was affected by dietary protein level, but not by dietary lipid level. Weight gain of fish fed the 50P‐15L (50% protein and 15% lipid) diet was higher than that of fish fed the 45% protein diets regardless of lipid level, but not different from that of fish fed the 50P‐11L (50% protein and 11% lipid), 50P‐19L (50% protein and 19% lipid), 55P‐11L (55% protein and 11% lipid), 55P‐15L (55% protein and 15% lipid) and 55P‐19L (55% protein and 19% lipid) diets. Feed consumption of fish was affected by dietary protein level, but not by dietary lipid levels. Feed efficiency ratio (FER) of fish was affected by dietary protein level, but not by dietary lipid level. Protein efficiency ratio (PER) of fish was affected by dietary protein level, but not by dietary lipid level. Nitrogen retention efficiency (NRE) of fish fed the 45P‐19L diet was higher than that of fish fed the 45P‐11L, 50P‐11L, 50P‐15L, 50P‐19L, 55P‐11L, 55P‐15L and 55P‐19L diets, but not different from that of fish fed the 45P‐15L diet. Moisture, crude protein and crude lipid contents of fish was affected by dietary protein and/or lipid level. Plasma triglyceride of fish was affected by dietary lipid level, but not by dietary protein level. In conclusion, optimum protein and lipid levels for growth and feed utilization (PER and NRE) for juvenile rockfish were 50% and 15%, and 45% and 19%, respectively, and the optimum dietary protein‐to‐energy ratio of 27.4 and 23.9 mg protein kJ^?1.     

Effects of dietary protein to energy ratios on growth and body composition of juvenile Chinese sucker,Myxocyprinus asiaticus

A growth experiment was conducted to investigate effect of dietary protein to energy ratios on growth and body composition of juvenile Myxocyprinus asiaticus (initial mean weight: 10.04 ± 0.53 g, mean ± SD). Nine practical diets were formulated to contain three protein levels (340, 390 and 440 g kg^?1), each with three lipid levels (60, 100 and 140 g kg^?1), in order to produce a range of P/E ratios (from 22.4 to 32.8 mg protein kJ^?1). Each diet was randomly assigned to triplicate groups of 20 fish in 400‐L indoors flow‐through circular fibre glass tanks provided with sand‐filtered aerated freshwater. The results showed that the growth was significantly affected by dietary P/E ratio (P < 0.05). Fish fed the diets with 440 g kg^?1 protein (100 and 140 g kg^?1 lipid, P/E ratio of 31.43 and 29.22 mg protein kJ^?1) had the highest specific growth rates (SGR) (2.16 and 2.27% day^?1, respectively). However, fish fed the diet with 390 g kg^?1 protein and 140 g kg^?1 lipid showed comparable growth (2.01% day^?1), and had higher protein efficiency ratio (PER), protein productive value (PPV) and energy retention (ER) than other groups (P < 0.05). No significant differences in survival were found among dietary treatments. Carcass lipid content was positively correlated with dietary lipid level, but irrespective of protein level and inversely correlated with carcass moisture content. Carcass protein contents increased with increasing dietary lipid at each protein level. The white muscle and liver composition showed that lipid increased with increasing dietary lipid level (P < 0.05). Dietary protein concentrations had significant effect on condition factor (CF), hepatosomatic index (HSI) and viscerosomatic index (VSI) (P < 0.05). However, dietary lipid concentrations had no significant effect on CF, HSI (P > 0.05). Based on these observations, 440 g kg^?1 protein with lipid from 100 to 140 g kg^?1 (P/E ratio of 29.22 to 31.43 mg protein kJ^?1) seemed to meet minimum requirement for optimal growth and feed utilization, and lipid could cause protein‐sparing effect in diets for juvenile Chinese sucker.     

不同蛋白质和脂肪水平对细鳞鲑幼鱼生长和肌肉氨基酸含量的影响

本研究旨在探讨不同蛋白质和脂肪水平对细鳞鲑(Brachymystax lenok)幼鱼生长、体成分以及肌肉氨基酸含量的影响。采用蛋白质水平为40%、45%、50%和55%,脂肪水平为8%和16%,共8组实验饲料。在水温为(16±0.2)℃的循环流水水族箱系统内进行为期10周的养殖试验。采用常规生化分析方法对该鱼肌肉营养学组成及含量进行测定分析。研究结果表明,不同蛋白和脂肪水平对细鳞鲑幼鱼增重率、特定生长率、肥满度和肝体比等均有显著影响(P0.05)。随着蛋白水平增加,增重率、特定生长率、肥满度和肝体比率先升高后降低,其肌肉粗蛋白含量也随之显著升高(P0.05),而对粗脂肪和粗灰分不存在显著影响;随着脂肪水平增加,其肌肉粗脂肪含量也随之显著提高(P0.05),而对水分、粗蛋白和灰分含量不存在显著影响。肌肉中共测定出17种氨基酸(除色氨酸),不同蛋白和脂肪水平对氨基酸总量(WTAA)和必需氨基酸的构成比例(WEAA/WTAA)不存在显著影响。综合生长性能与氨基酸模式的实验结果,本研究认为细鳞鲑幼鱼最适蛋白质和脂肪水平分别为50%和8%,适宜蛋能比为29.36 g/MJ。     

Effects of dietary protein and lipid levels with different protein‐to‐energy ratios on growth performance,feed utilization and body composition of juvenile red‐spotted grouper,Epinephelus akaara

An 8‐week feeding trial was conducted to assess dietary protein and lipid levels on growth performance, feed utilization and body composition of juvenile red‐spotted grouper (7.85 ± 0.03 g fish^?1). Nine semi‐purified diets were formulated containing varying protein levels (440–520 g kg^?1, dry matter) and lipid levels (60–120 g kg^?1, dry matter). The weight gain of juvenile Epinephelus akaara was affected by dietary protein (p = .005) and its interaction with dietary lipid (p = .020). Viscerosomatic index, intraperitoneal fat ratio and whole‐body lipid level increased with increasing dietary lipid level (p < .001). Nitrogen retention was not affected by dietary protein and lipid, while lipid retention decreased with increasing dietary lipid level (p < .001). The plasma blood urea nitrogen increased with increasing dietary protein level (p = .003). This study showed that diet with 520 g kg^?1 protein and 60 g kg^?1 lipid with 30.58 mg kJ^?1 P:E provided a maximal growth for this species. Moreover, an increase in dietary lipid levels (from 60 to 90 g kg^?1) could reduce the protein requirement (from 520 to 480 g kg^?1) without affecting the growth performance, while higher fat deposition was observed in fish fed high‐lipid diets.     

Effects of dietary starches and the protein to energy ratio on growth and feed efficiency of juvenile cobia,Rachycentron canadum

Optimization of the protein to energy ratio in juvenile cobia (Rachycentron canadum) would allow the production of diets that maximize growth without the addition of excess energy that may increase costs or even be detrimental to the health of the fish. During a 6‐week growth trial, juvenile cobia (5.6 ± 0.5 g fish^?1 initial weight) were fed five isonitrogenous and isolipidic diets containing various protein to energy ratios using starch as the energy source. At the end of the trial, some fish were analysed for body composition characteristics while the rest were used to examine the excretion of dietary starch in the feces. Survival and growth were not significantly affected, but feed efficiency (ranging from 0.64 to 0.94) and daily consumption (ranging from 45.3 to 64.1 g kg^?1 of body weight d^?1) were affected. No reduction in consumption due to excess energy was noted. Analysis of the fecal carbohydrate data showed a linear relationship between dietary inclusion and excretion of carbohydrates with no sign of reaching saturation. Results of this study suggest that cobia can utilize dietary carbohydrates up to at least 340 g kg^?1 of dry diet with an optimal protein to energy ratio of approximately 34 mg protein kJ^?1metabolizable energy.