不同蛋白质和小麦淀粉水平对大黄鱼生长性能、糖酵解和糖异生关键酶活性的影响

本实验旨在研究不同蛋白质和小麦淀粉水平对大黄鱼生长性能、肝脏糖酵解和糖异生关键酶活性、血清指标、糖原含量及消化酶活性的影响。采用2×3双因素实验设计,共配制6组饲料,包含2个蛋白质水平(41%、46%)和3个小麦淀粉水平(10%、20%、30%),选取初重约为(14.84±0.16) g的大黄鱼900尾,随机分为6组(每组3个重复,每个重复50尾),进行8周的养殖实验。实验结果表明:饲料蛋白质和小麦淀粉水平的交互作用对大黄鱼增重率和特定生长率无显著影响(P>0.05),且在相同的饲料蛋白质水平下,饲料小麦淀粉水平对大黄鱼增重率和特定生长率无显著影响(P>0.05)。饲料蛋白质和小麦淀粉的交互作用对大黄鱼肝脏6-磷酸果糖激酶(phosphofructokinase,PFK)、丙酮酸激酶(pyruvate kinase,PK)、果糖-1,6-二磷酸酶(fructose-1,6-bisphosphatase,FBPase)活性有显著影响(P<0.05),但对葡萄糖激酶(glucokinase,GK)、葡萄糖-6-磷酸酶(glucose-6-phosphatase,G6Pase)、磷酸烯醇式丙酮酸羧激酶(phosphoenolpyruvate,PEPCK)活性无显著影响(P>0.05)。当饲料蛋白质水平为41%时,饲料小麦淀粉水平对葡萄糖激酶、6-磷酸果糖激酶和果糖-1,6-二磷酸酶活性有显著影响(P<0.05),且果糖-1,6-二磷酸酶活性随着饲料小麦淀粉水平的升高呈下降趋势,但对丙酮酸激酶、葡萄糖-6-磷酸酶、磷酸烯醇式丙酮酸羧激酶活性无显著影响(P>0.05);当饲料蛋白质水平为46%时,饲料小麦淀粉水平对葡萄糖激酶、6-磷酸果糖激酶、丙酮酸激酶、果糖-1,6-二磷酸酶活性有显著影响(P<0.05),且葡萄糖激酶、6-磷酸果糖激酶、丙酮酸激酶均随饲料小麦淀粉水平的升高呈上升趋势,但对葡萄糖-6-磷酸酶和磷酸烯醇式丙酮酸羧激酶活性无显著影响(P>0.05)。实验表明,大黄鱼在高蛋白质水平下能够有效调节糖酵解和糖异生关键酶活性,降低血糖含量及丙氨酸转氨酶、天冬氨酸转氨酶活性,并且未显著影响增重率;在低蛋白质水平,血糖含量和肝糖原含量随小麦淀粉水平的升高呈上升趋势,但增重率随着饲料小麦淀粉水平的升高呈上升趋势,表明在低蛋白质水平下高小麦淀粉水平对大黄鱼的生长有一定的改善作用。     

不同小麦淀粉和脂肪水平对大黄鱼的生长性能、饲料利用及糖代谢关键酶活力的影响

为探讨饲料中添加不同小麦淀粉和脂肪水平对大黄鱼幼鱼生长、饲料利用以及糖代谢关键酶活力的影响,进行了为期8周的生长实验。设计了3个小麦淀粉水平(5%、10%和30%)和2个脂肪水平(5%和10%)的3×2的两因子实验,配制了6种等氮的饲料,分别喂养平均体质量为(6.75±0.12)g的大黄鱼幼鱼。结果显示,饲料中小麦淀粉和脂肪水平对大黄鱼增重率(WG)、特定生长率(SGR)、饲料效率(FE)、成活率(SR)、肝体比(HSI)和肥满度(CF)无显著交互作用,对脏体比(VSI)有显著交互作用。在同一脂肪水平下,淀粉水平为30%组WG和SGR显著高于10%淀粉组。不同小麦淀粉和脂肪水平对肝糖原含量无显著交互作用,而对肌糖原含量有显著交互作用,在饲料脂肪水平为5%时,30%小麦淀粉水平下的肝糖原含量显著高于10%和20%淀粉水平,10%淀粉水平下的肌糖原含量显著高于20%和30%淀粉水平;在脂肪水平为10%时,10%淀粉水平下的肝糖原含量显著高于20%和30%淀粉水平,而30%小麦淀粉水平下的肌糖原含量显著高于10%和20%淀粉水平。小麦淀粉和脂肪水平对血清中谷丙转氨酶(ALT)、谷草转氨酶(AST)、总胆固醇(TC)和葡萄糖(GLU)含量无显著交互作用,对总蛋白(TP)和甘油三酯(TG)交互作用显著。不同小麦淀粉和脂肪水平对肝脏脂肪酶活性有显著的交互作用,对淀粉酶活性无显著交互作用;同一脂肪水平下,脂肪酶的活性随着淀粉水平的升高而升高,同一饲料淀粉水平下,饲料脂肪水平为10%组的脂肪酶活性显著高于5%组。不同小麦淀粉和脂肪水平对肝脏丙酮酸激酶(PK)的活性有显著的交互作用,而对葡萄糖激酶(GK)、磷酸果糖激酶(PFK)、磷酸烯醇式丙酮酸羧激酶(PEPCK)、1,6-二磷酸果糖酶(FBPase)和6-磷酸葡萄糖酶(G6Pase)的活性均无显著交互作用。研究表明,当饲料脂肪水平为5%时,大黄鱼能够通过调节糖酵解关键酶活性及肝糖原含量来维持血糖平衡,改善对小麦淀粉的利用能力;而当脂肪水平为10%时,大黄鱼对小麦淀粉的利用能力降低。     

饲料碳水化合物水平及饥饿处理对斜带石斑鱼生长及葡萄糖耐受能力的影响

为揭示斜带石斑鱼对碳水化合物利用的特点,研究了3个碳水化合物水平及饥饿处理对其生长、血浆生化指标及肝/肌糖原的影响。实验选取300尾初重为(35±0.28)g的幼鱼,设置持续投喂高(35%,CH)、中(21%,CM)、低(7%,CL)3个碳水化合物水平组,以及持续投喂组(CM)、饥饿再投喂组(R,饥饿4周+投喂4周,投喂CM组饲料)、饥饿组(S)3个投喂模式组。饲养8周后饥饿24 h,以30 mg/100 g体质量腹腔注射葡萄糖研究其代谢反应。结果显示,增重率和特定生长率随饲料碳水化合物水平的增加而升高,但无显著差异,饲料系数以CL组最高。不同碳水化合物水平下,各组注射葡萄糖后1~3 h血糖水平达峰值,但CM组在6 h内迅速回到注射前水平;各组血浆胰岛素水平均先降后升,但CL组在3 h后急剧下降;各组肝糖原、血浆甘油三酯含量在注射后1 h内均显著上升。饥饿处理下,持续投喂组(CM)血糖水平在6 h时迅速恢复至注射前水平;CM组和R组血浆胰岛素在1 h内显著下降,但S组持续上升;CM组血浆甘油三酯含量在0~6 h内显著高于其他两组。研究表明,饲喂中等水平碳水化合物(21%)比较符合斜带石斑鱼糖耐受能力,而饥饿处理下则以持续投喂组糖耐受能力最强。     

不同糖源对达氏鲟幼鱼生长、体成分及生理生化指标的影响

分别以糊精、小麦淀粉、玉米淀粉、α-淀粉(预糊化玉米淀粉)、蔗糖、葡萄糖为糖源,配制6种等氮等能的半纯化饲料,喂养达氏鲟(Acipenser dabryanus)幼鱼(68.05 g±1.63 g)8周,研究饲料中糖源对达氏鲟幼鱼生长性能、体成分及生理生化指标的影响。结果发现糊精、小麦淀粉、玉米淀粉、α-淀粉组实验鱼饲料效率和蛋白质效率显著高于蔗糖和葡萄糖组(P0.05),玉米淀粉组实验鱼增重率、特定生长率和饲料效率最高。不同糖源对达氏鲟肥满度影响不显著(P0.05),而对肝体比和脏体比均影响显著(P0.05)。肝体比和脏体比最高的为葡萄糖组,最低的为小麦淀粉组。小麦淀粉组全鱼、肌肉和肝中粗蛋白含量最高,葡萄糖组全鱼和肌肉的粗蛋白含量最低且均显著低于其他各组(P0.05)。糊精、蔗糖和葡萄糖组全鱼和肌肉粗脂肪显著高于其他各组(P0.05)。α-淀粉组肝糖原显著高于其他各组(P0.05),α-淀粉组和葡萄糖组肌糖原显著高于其他各组(P0.05)。肝和血液中甘油三酯和总胆固醇含量和肌体和血液中糖水平呈正相关。不同糖源对达氏鲟消化道消化酶和肝丙酮酸激酶、磷酸烯醇式丙酮酸激酶活性影响显著(P0.05),对肝己糖激酶、磷酸烯醇式丙酮酸羧化酶活性影响不显著(P0.05)。研究结果表明,在饲料中添加玉米淀粉作为糖源更有利于达氏鲟幼鱼生长。     

饲料中不同种类的碳水化合物对大菱鲆生长性能和代谢反应的影响

为探讨在低蛋白水平(40%)下,饲料中不同种类的碳水化合物(葡萄糖、蔗糖和糊精)对大菱鲆幼鱼[(8.12±0.04)g]生长、成活、饲料利用、体组成和血液生理生化指标等的影响,实验在对照组饲料中未添加可消化碳水化合物,含40%的蛋白质和18%的脂肪,然后在对照组饲料的基础上,调节脂肪水平为12%,分别添加15%的葡萄糖、蔗糖和糊精配制3组实验饲料。在流水式养殖系统中进行9周的大菱鲆生长实验。结果显示,各处理组大菱鲆成活率均高于95.24%,并且各组间无显著差异;对照组和糊精组大菱鲆的增重率(WGR)和特定生长率(SGR)均显著高于葡萄糖组和蔗糖组。各组间的日摄食率(DFI)没有显著差异。对照组和糊精组饲料效率(FE)显著高于蔗糖组,但葡萄糖组FE与其它各组无显著差异;各处理组间蛋白质和脂肪表观消化率(ADC)未受碳水化合物种类的显著影响,而可消化碳水化合物的ADC依次为:葡萄糖组>糊精组>蔗糖组(。葡萄糖组的能量ADC最高,蔗糖组的最低;除对照组肌肉脂肪含量显著高于其它各组外,碳水化合物的种类对大菱鲆肌肉常规组成及糖原含量无显著影响,但显著影响了肝脏的脂肪和糖原含量。大菱鲆肝脏脂肪含量依次为对照组>糊精组>蔗糖组>葡萄糖组,肝脏糖原含量依次为葡萄糖组>蔗糖组>糊精组>对照组;不同碳水化合物种类对大菱鲆幼鱼血浆葡萄糖含量没有显著影响,但显著影响血浆总氨基酸、胰岛素、总胆固醇(CHO)和甘油三酯(TAGs)的含量。结果表明,本实验条件下,大菱鲆对糊精的利用效率优于葡萄糖和蔗糖,并且不同种类的碳水化合物通过糖脂关联代谢等途径对大菱鲆幼鱼的体组成和血液生理生化指标造成一定的影响。     

腹腔注射葡萄糖对大黄鱼血液生化指标及糖代谢关键酶表达量的影响

为研究大黄鱼对葡萄糖的耐受能力和相关糖代谢关键酶的表达量,选取体质量约为100 g的大黄鱼禁食24 h,随机分为3个实验组,分别为对照组(0.9%的无菌生理盐水,CG组),低剂量葡萄糖组(300 mg/kg体质量,LG组)和高剂量葡萄糖组(1500 mg/kg体质量,HG组)。结果显示,大黄鱼在注射高剂量和低剂量葡萄糖后,血糖均在3 h达到最高水平,且HG组的峰值显著高于LG组,LG组在24 h恢复至正常水平,HG组在24 h仍然高于正常水平。HG组、LG组注射葡萄糖后,HK、GK基因相对表达量均显著上升,其峰值出现在注射后9 h。HG组PFK基因相对表达量在注射后6 h达到峰值。HG组PEPCK基因相对表达量在注射葡萄糖后显著下降,其中最低时间点为2 h。HG组G6PD基因相对表达量在注射后6 h显著高于其他各个时间点。研究表明,注射高、低浓度葡萄糖后,均会提高大黄鱼血糖水平,且能维持较长时间。注射葡萄糖后糖酵解途径关键酶如HK、GK、PFK及糖异生途径关键酶PEPCK基因相对表达量受血糖调节,但G6Pase、FBPase表达量并不因血糖升高而下降。导致注射葡萄糖后,大黄鱼不断产生内源性葡萄糖,这是大黄鱼表现为对高血糖不耐受的原因之一。     

饲料中不同蛋白质和淀粉水平对斜带石斑鱼生长性能和肝脏相关代谢酶活性的影响

为了探讨饲料蛋白质和碳水化合物对斜带石斑鱼的互作效应,实验采用3×3因子设计,配制蛋白质水平(P)为38%、45%和52%,淀粉水平(S)为10%、20%和30%的9种实验饲料,分别饲喂斜带石斑鱼56 d。结果显示,38%粗蛋白与10%淀粉饲料组(38P/10S饲料组)增重率显著低于其他各组,52P/10S组增重率最高,但与45P/20S、45P/30S、52P/20S组差异不显著。增加饲料蛋白质或淀粉水平显著增加饲料效率、鱼体蛋白质与脂肪含量及肝糖原肝脂含量,而降低摄食率和鱼体水分含量。增加饲料蛋白质水平降低蛋白质效率,但增加淀粉水平却增加蛋白质效率及肝体比与脏体比。饲料蛋白质水平和淀粉水平对鱼体灰分含量无明显影响。肝中肝酯酶、脂蛋白酯酶、脂肪酸合成酶、谷丙转氨酶和谷草转氨酶活性均随蛋白质或淀粉水平的升高呈显著上升趋势。增加饲料蛋白质水平显著降低肝中葡萄糖-6-磷酸酶活性,而增加肝中苹果酸酶活性,但对肝中葡萄糖激酶、丙酮酸激酶、磷酸果糖激酶、磷酸烯醇式丙酮酸羧激酶和葡萄糖-6-磷酸脱氢酶活性没有明显影响。增加饲料淀粉水平显著增加肝中葡萄糖激酶、丙酮酸激酶、磷酸果糖激酶、葡萄糖-6-磷酸脱氢酶和苹果酸酶活性,但显著降低磷酸烯醇式丙酮酸羧激酶和葡萄糖-6-磷酸酶活性。上述结果显示,斜带石斑鱼的生长和肝脏代谢明显受饲料蛋白质和淀粉水平的影响,其中,糖代谢酶活性受淀粉水平的影响较大,而受饲料蛋白质水平的影响较小,斜带石斑鱼生长适宜的饲料蛋白质和淀粉水平分别为45%和20%。     

饲料中维生素A对青鱼幼鱼生长、血清生化指标和肝脏糖脂代谢酶活性及基因表达的影响

为研究饲料中维生素A(VA)对青鱼幼鱼生长、血清生化指标和肝脏糖脂代谢相关酶活性及基因表达的影响,实验选取360尾初始体质量为(6.10±0.10) g的青鱼幼鱼,随机分配至3个实验组中,每个实验组设置3个平行。采用单因素实验设计,以无维酪蛋白和明胶为蛋白源、菜籽油为脂肪源、糊精为糖源,同时添加矿物质混合物和维生素混合物(无VA添加)配制成3组实验饲料,分别以饲料1 (Diet1)、饲料2 (Diet2)和饲料3 (Diet3)表示。在饲料1、饲料2和饲料3中分别添加0、2 200和20 000 IU/kg VA醋酸酯(500 000IU/g),经高效液相色谱法(Agilent-1100, Agilent,美国)检测后实验饲料中VA的实际含量分别为178.2、2 058.9和18 436.2 IU/kg,养殖周期为8周。结果显示:饲料中VA缺乏会显著降低青鱼幼鱼的增重率(WGR)和特定生长率(SGR);VA缺乏会显著降低血清血糖(GLU)、甘油三酯(TG)和低密度脂蛋白(LDL)浓度,增加总胆固醇(TCH)浓度。饲料中添加2 058.9IU/kg VA能显著提高肝脏己糖激酶(HK)、磷酸果糖激酶(PFK)、丙酮酸激酶(PK)活性,促进葡萄糖转运蛋白-2 (GLUT-2)、HK、葡萄糖激酶(GK)、PFK和葡萄糖-6-磷酸酶(G6Pase)基因表达。当饲料中VA含量为2 058.9 IU/kg时,对肝脏脂肪酸转运蛋白-1(FATP-1)基因表达无显著影响,但显著影响肉碱棕榈酰转移酶-1 (CPT-1)和肉碱棕榈酰转移酶-2 (CPT-2)基因表达。当饲料中VA缺乏时,CPT-1和CPT-2基因表达受到显著性抑制;当饲料中添加过量VA时,乙酰辅酶A羧化酶-2 (ACC-2)和脂蛋白酯酶(LPL)基因表达受到抑制;同时,VA过量组中肝脏过氧化物酶体增殖物激活受体-γ(PPAR-γ)基因表达显著下降。研究表明,在饲料中添加2 058.9 IU/kg VA可以促进青鱼幼鱼生长,提高肝脏对葡萄糖的转运能力,促进糖酵解和糖异生代谢平衡,同时促进脂肪酸合成和转运。     

真鲷营养需要量及饲料添加剂（下）

三、碳水化合物真鲷对碳水化合物利用能力较差。古市试验指出,饲料中不添加葡萄糖,真鲷生长和饲料效率极差。Ｃｈｉｔｔｉｎｅ也指出,配制含３０%～４０%碳水化合物的饲料喂养真鲷,其生长率和饲料转化率都很低。Ｂｕｈｌｅｒ和古市等研究表明,真鲷对葡萄糖消化吸收率最高,其次是麦芽糖、糊精、淀粉,分子量越高的碳水化合物消化吸收效果越差。单糖类的营养价,葡萄糖优于果糖、乳糖、葡萄糖胺。米康夫实验表明,真鲷对糊精利用率为９２%～９９%,α-淀粉为２２%～３５%,β-淀粉为３５%。同时他又发现,分别以含２５%的葡萄糖、糊精和α-淀粉的饲…     

日粮中碳水化合物类型对多鳞白甲鱼幼鱼生长性能、体组成及健康状况的影响

为探究多鳞白甲鱼幼鱼日粮中最佳碳水化合物添加类型，以葡萄糖、麦芽糖、糊精、玉米淀粉及纤维素5种碳水化合物为糖源，分别配制5种日粮，对多鳞白甲鱼幼鱼进行了为期56 d的养殖实验。结果显示，(1)生长及饲料利用率方面，麦芽糖组的终末体重、特定生长率、饵料系数以及蛋白质效率等指标最佳，纤维素组最差。(2)体成分方面，纤维素组全鱼粗脂肪水平最低，粗灰分水平显著高于麦芽糖组，麦芽糖组及纤维素组肌糖原含量最低，糊精组肝糖原含量最低。(3)主成分分析表明，C16:0、SFA、MUFA和PUFA比例对肝胰脏脂肪酸比例产生主要影响，其中，C16:0和SFA比例在麦芽糖组显著提高，MUFA比例在糊精组显著提高，而PUFA在纤维素组显著提高；C18:1n-9和MUFA比例对肌肉和脂肪组织总体脂肪酸组成产生主要影响，二者比例在麦芽糖组显著提高。(4)血清生化指标方面，麦芽糖组及纤维素组谷丙转氨酶活性、麦芽糖组谷草转氨酶活性显著较高，葡萄糖组及纤维素组碱性磷酸酶活性、球蛋白含量较高，而血糖含量反之。(5)抗氧化能力方面，麦芽糖组肝胰脏过氧化氢酶、总超氧化物歧化酶、谷胱甘肽过氧化物酶活性最高，纤维素组丙二醛含量最...     

Effects of dietary carbohydrate sources on the growth performance and hepatic carbohydrate metabolic enzyme activities of juvenile cobia (Rachycentron canadum Linnaeus.)

An 8-week feeding trial was conducted to evaluate the effect of dietary carbohydrate sources on the growth performance and hepatic carbohydrate metabolic enzyme activities of juvenile cobia. Six experimental diets were formulated to contain 20% glucose, sucrose, maltose, dextrin, corn starch and wheat starch respectively. The results indicated that fish fed the wheat starch and dextrin diets showed significantly better weight gain, specific growth rate and protein efficiency ratio compared with those fed the other diets. However, fish fed the glucose diet had a significantly lower survival and condition factor than those fed the other diets. There were significant differences in the total plasma glucose and triglyceride concentration in fish fed diets with different dietary carbohydrate sources. Haematocrit, haemoglobin, red blood cell and leucocytes were significantly affected by the dietary carbohydrate sources. The activities of glucose-6-phosphate dehydrogenase (G6PD), 6-phosphofructokinase (PFK) and fructose-1,6-bisphosphatase (FBPase) were significantly affected by the dietary carbohydrate sources, while fish fed the glucose diet showed higher G6PD, PFK and FBPase activities than those fed the other diets. These data indicated that dextrin and wheat starch were the most optimal carbohydrate sources for juvenile cobia.     

Carbohydrate utilization by juvenile silver perch, Bidyanus bidyanus (Mitchell). III. The protein-sparing effect of wheat starch-based carbohydrates

The ability of juvenile silver perch (Bidyanus bidyanus) to utilize dietary raw wheat meal, raw wheat starch, gelatinized wheat starch and dextrin as energy sources to spare protein for growth was quantified. Energy utilization and protein sparing were assessed by comparing the weight gain, energy retention efficiency, protein retention and body composition of silver perch that had been fed a series of diets in which the basal diet (low carbohydrate) was systematically replaced with graded levels of each carbohydrate ingredient or an inert diluent, diatomaceous earth. The protein content decreased as the carbohydrate content increased, giving four different protein to energy ratios for each of the four carbohydrate sources (except for the 60% inclusion level, at which only three carbohydrate sources were tested). Silver perch were efficient at utilizing carbohydrate for energy to spare protein. Silver perch fed diets containing up to 30% wheat meal, raw wheat starch, gelatinized wheat starch or dextrin exhibited similar growth, protein retention and energy retention efficiency to the fish fed the basal diet. Weight gain of silver perch fed diets containing wheat meal or carbohydrates at 45% inclusion content had significantly reduced weight gain when compared with fish fed the basal diet. However, protein retention and energy retention efficiency were similar or better. Whole‐body protein levels of silver perch remained constant regardless of carbohydrate sources, and there was no evidence of increasing whole‐body lipid concentrations for fish fed diets with up to 60% dietary carbohydrate. Silver perch were more efficient at utilizing processed starch (either gelatinized starch or dextrin) than wheat meal or raw wheat starch.     

Effects of Amylopectin/Amylose Starch Ratio on Growth, Body Composition and Glycemic Response of Sunshine Bass Morone chrysops × M. saxatilis

Manipulation of the ratio of amylopectin (α‐[1,4] and α‐[1,6] linked glucose) to amylose (α‐[1,41 linked glucose) starches in the carbohydrate fraction of the diet has been used to improve carbohydrate and lipid metabolism in mammalian models. A 10‐wk feeding trial was conducted to determine the effect of dietary amylopectin/amylose ratio on growth and composition of growth of advanced sunshine bass (Morone chrysops × M. saxatilis) fingerlings (60 g, initial weight). Fish were fed cold‐pelleted, semipurified, isonitrogenous (35% crude protein), isocaloric (3.6 kcaVg protein), isolipidic (5%) diets containing 25% carbohydrate. The carbohydrate fraction of the diets was composed of either glucose, dextrin, 100% amylopectin/0% amylose, 70% amylopectin/30% amylose, or 30% amylopectin/70% amylose. Diets differing in ratios of amylopectin/amylose were achieved by adjusting the proportion of high‐amylopectin (100% amylopectin) to high‐amylose (70% amylose) corn starch. Diets were fed to fish in quadruplicate 76‐L tanks (seven fish/tank) connected to a brackish water (5‐7%v) recirculating culture system with biofiltration. Weight gain ranged from 195 to 236% of initial weight (60 g) and was significantly greater (P < 0.1) for fish fed diets containing 25% carbohydrate as dextrin or as 70% amylose and significantly lower in fish fed diets in which carbohydrate was composed of 30% amylose, 100% amylopectin, or glucose. Feed efficiency ranged from 0.52 to 0.61 and was higher in fish fed the diet containing the highest concentration of amylose and lower in fish fed the diet containing glucose. Hepatosomatic index was highest (2.71) in fish fed the diet containing glucose and lowest (1.401.45) in fish fed diets containing high‐amylose cornstarch. Intraperitoneal fat ratio was distinctly lower in fish fed diets containing some amylose as compared to those fed diets without amylose. Liver lipid was significantly lower (4.8%) in fish fed the diet containing glucose and almost twice as high (7.3‐8.9%) in fish fed the diets containing any starch. Glycogen content of the liver decreased from approximately 12% in fish fed the diet containing glucose to 5% in fish fed the diets containing amylose. Muscle proximate composition and ratio were unaffected by the dietary treatments. Fasting levels (15 h) of blood glucose in fish reared for 10 wk on the diet containing glucose were significantly elevated (5.5 mmol/L) when compared to fasting levels of those that had been reared on diets containing starch (3.4‐1.1 mmol/L). Fish fed the diet containing glucose exhibited maximum blood concentrations (14.6 mmoVL) 4 h postprandial then rapidly declined to nearly fasting levels within 8 h postprandial. In contrast, maximum plasma glucose concentrations in fish fed diets containing starch were roughly half (6.8‐8.1 mmol/L) those of fish fed the diet containing glucose. Blood glucose in fish fed diets containing dextrin or predominantly amylopectin starch remained elevated longer than that of fish fed diets containing glucose or predominantly amylose starch. Glycemic response appeared to decrease with increasing dietary amylose content. These data suggest that feeding diets in which a greater portion of the starch is amylose may be a useful strategy for improving carbohydrate use in sunshine bass.     

Utilization of different carbohydrate sources and starch forms by bagrid catfish (Mystus nemurus) (Cuv & Val)

Two experiments were conducted to ascertain the utilization of different carbohydrate sources and different forms of starch present in bagrid catfish (Mystus nemurus) fry. The nutritional quality and starch forms of cornstarch, dextrin, broken rice, and sago flour were evaluated in a 4 × 2 factorial design. All diets were formulated to be isonitrogenous (400 g kg^?1 crude protein) and isolipidic (150 g kg^?1 crude lipid), fed to triplicate groups of bagrid catfish fry (initial weight 6.04 ± 0.04 g). Growth studies, enzymatic response and postprandial plasma glucose were observed. A two‐way anova (P > 0.05) analysis of the data obtained showed that the final body weight, specific growth rate (SGR) and food conversion ratio (FCR) were significantly affected by carbohydrate source, but not significantly affected by starch form. Fish fed broken rice and corn starch had similar SGR and FCR compared to fish fed with dextrin and sago flour. The postprandial plasma glucose trend in fish fed with corn starch and broken rice showed a gradual increase while sago flour and dextrin‐fed fish peaked at 2 and 3 h, respectively. Lipogenic enzyme (G6PDH) activity were more pronounced than gluconeogenic enzyme (ME) in M. nemurus irrespective of carbohydrate source and starch form. Therefore, we suggest that raw broken rice and corn starch are suitable carbohydrate sources in the M. nemurus diet.     

Growth performance and metabolic utilization of diets including starch,dextrin, maltose or glucose as carbohydrate source by gilthead sea bream (<Emphasis Type="Italic">Sparus aurata</Emphasis>) juveniles

The effect of dietary carbohydrate complexity on growth, feed utilization and activity of selected key liver enzymes of intermediary metabolism were studied in gilthead sea bream juveniles. Four isonitrogenous (50% crude protein) and isolipidic (16% crude lipids) diets were formulated to contain 20% of pregelatinized maize starch, dextrin, maltose or glucose. Triplicate groups of fish (117 g initial weight) were fed each diet to near satiation during 6 weeks. No effect of dietary carbohydrate on growth was noticed. Feed efficiency was lower in fish fed the glucose diet than the maltose and dextrin diets. The lowest protein efficiency ratio was observed in fish fed the glucose diet. Six hours after feeding, glycemia was higher in fish fed the glucose diet than the maltose and starch diets. Liver glycogen content was unaffected by dietary carbohydrate complexity. Hepatic glucokinase (GK) activity was higher in fish fed the glucose and the maltose diets, while higher pyruvate kinase (PK) activity was recorded in fish fed the glucose diet than in fish fed the starch diet. Fructose-1,6-bisphosphatase (FBPase) and glucose-6-phosphate dehydrogenase (G6PD) activities were higher in fish fed the starch diet compared to dextrin and glucose diets. Data suggest that dietary glucose and maltose are more effective than complex carbohydrates in enhancing liver glycolytic activity. Dietary glucose also seems to be more effective than starch in depressing liver gluconeogenic and lipogenic activities. Overall, dietary maltose, dextrin or starch was better utilized than glucose as energy source by gilthead sea bream juveniles.     

不同糖源饲料对卵形鲳鲹(Trachinotus ovatus)生长、体组成、血糖水平和肝脏糖酵解酶活力的影响

分别以葡萄糖、蔗糖、糊精、玉米淀粉和糊化玉米淀粉为糖源配制成5种等氮等脂饲料,对初始体重为(31.24±0.58) g 的卵形鲳鲹(Trachinotus ovatus)进行为期56 d 的饲养实验,比较不同糖源饲料对卵形鲳鲹生长、体组成、血液指标和糖酵解酶活力的影响,筛选出最有利于生长的糖种类。结果显示,不同糖源对卵形鲳鲹增重率(WG)和特定生长率(SGR)均有显著影响(P<0.05),且随糖分子量增大有增大的趋势,其中,糊化玉米淀粉的 WG 和 SGR 最高分别为335.35%和2.62%/d;不同糖源组的脏体比(VSI)、肝体比(HSI)、肝糖原和肌糖原含量以及血糖、血浆总胆固醇和甘油三酯也有显著性差异(P<0.05),且均为葡萄糖组最高;除己糖激酶(HK)活力外,各糖源组的其他糖酵解酶活力均有显著性差异(P<0.05),亦是葡萄糖组最高。在本实验条件下,卵形鲳鲹对淀粉类大分子糖的利用效果优于葡萄糖等小分子糖类,糊化玉米淀粉组的生长效果最好;不同糖源饲料对卵形鲳鲹糖代谢过程中糖原合成、糖脂转化、糖酵解等途径的相关指标有一定影响。     

Growth,Feed Utilization,and Glycemic Response in European Sea Bass,Dicentrarchus labrax,Juveniles Fed Carbohydrate of Different Complexities

The effect of dietary carbohydrate complexity on growth, feed utilization, and glycemia was studied in European sea bass juveniles. Four isonitrogenous (50% crude protein) and isolipidic (15% crude lipids) diets were formulated to contain 20% pregelatinized maize starch (PGS diet), dextrin (DEX diet), maltose (MAL diet), or glucose (GLU diet). No effect of dietary carbohydrate complexity on growth was noticed. Feed efficiency and protein efficiency ratio were lower in fish fed the GLU diet than in the other groups, whereas the opposite was observed for feed intake. Plasma glucose peaked 3–4 h after feeding in fish fed the MAL and GLU diets, whereas in fish fed the PGS and DEX diets the peak was reached 5–6 h after feeding. Peak plasma glucose concentration (13 mmol/L) was higher in fish fed the GLU diet than the other diets (9 mmol/L). Shorter hyperglycemia duration was observed in fish fed the MALT and GLU diets (6 h) than the PGS and DEX diets (10 h). Complex carbohydrates delayed plasma glucose concentration peak compared with simple sugars, whereas the opposite was observed for hyperglycemia duration. Overall, dietary maltose, dextrin, and starch were apparently better utilized as energy source than glucose by European sea bass juveniles.     

The effect of dietary carbohydrates on the growth response,digestive gland glycogen and digestive enzyme activities of early spiny lobster juveniles,Jasus edwardsii

The effect of various carbohydrate sources (glucose, sucrose, agar, wheat, tapioca, maize, potato and dextrin), and inclusion levels of gelatinized maize starch (0, 70, 170, 270 g kg^?1), incorporated in semi‐purified diets on the performance [growth, survival, food consumption (FC), enzyme activity and glycogen content of the digestive gland (DG)] of spiny lobster juveniles was investigated in a 12‐week culture experiment. There was no difference in specific FC among diets (1.1% BW day^?1), but lobsters fed with fresh mussel grew significantly faster (specific growth rate = 1.8% BW day^?1) than on the formulated diets (0.9–1.1% BW day^?1). None of the carbohydrate supplements tested produced a significant improvement in growth or survival over a basal control diet. However, the diet containing 270 g kg^?1 native wheat starch resulted in the highest moulting (mean = 2.1 moults per lobster), glycogen (3.3 mg g^?1) and free glucose (1.1 mg g^?1) concentrations among lobsters fed with the formulated diets, suggesting a superior utilization of this source of carbohydrate. The greater glycogen (8.0 mg g^?1 tissue) and free glucose (2.0 mg g^?1 tissue) concentrations, as well as higher specific activity of α‐amylase (2.3 versus <0.7 U mg^?1 for other diets), found in the DG of lobsters fed with fresh mussel indicated a metabolism strongly directed to the utilization of glycogen.