饲料中添加酵母提取物对凡纳滨对虾免疫相关基因表达及抗菌机能的影响

为了评估饲料中添加酵母提取物对凡纳滨对虾免疫灵敏性和平衡性的相关基因表达的影响,以鱼粉含量为24.5%的基础饲料(对照组)及在基础饲料中添加2.5%酵母提取物的实验饲料,分别饲喂凡纳滨对虾56 d,检测两种饲料投喂的对虾在急性感染溶藻弧菌前后鳃组织Toll受体、IM D和溶菌酶mRNA表达量变化及感染后的对虾死亡情况。结果表明:摄食添加酵母提取物饲料的凡纳滨对虾鳃组织中Toll受体mRNA和溶菌酶mRNA表达量均显著高于对照组对虾(P0.05),IMD mRNA表达量与对照组无显著性差异(P0.05)。急性感染溶藻弧菌后,两组对虾鳃组织Toll受体、IMD和溶菌酶mRNA表达量随感染进程均出现显著变化,Toll受体、IMD和溶菌酶mRNA表达量峰值出现的时间分别为24、42和36 h,且摄食添加酵母提取物组对虾各基因的表达量峰值分别为对照组峰值的201.06%、481.46%和276.77%,均显著高于对照组对虾(P0.05)。摄食添加酵母提取物饲料组对虾鳃组织中Toll受体和IM D mRNA表达量在感染溶藻弧菌后12和24 h分别出现显著上调,而对照组对虾鳃组织中Toll受体和IMD mRNA表达量分别在感染弧菌后24和42 h才出现显著上调。两组对虾经溶藻弧菌人工急性感染后72 h内的累积死亡率无显著差异(P0.05)。实验表明,饲料中添加酵母提取物上调了溶藻弧菌感染前凡纳滨对虾Toll受体和溶菌酶mRNA的表达量,提早了溶藻弧菌感染后对虾Toll受体和IMD mRNA表达量上调时间,且增加了对虾Toll受体、IM D和溶菌酶mRNA表达量的峰值,在一定程度上提高了凡纳滨对虾免疫相关基因表达的灵敏性。     

酵母提取物替代鱼粉对凡纳滨对虾消化机能的影响

为探明使用经氨基酸平衡后的酵母提取物替代鱼粉对凡纳滨对虾消化机能的影响,分别用酵母提取物替代饲料中15 %(B)、30 %(C)、45 %(D)、60 %(E)和100 %(F)的鱼粉,配制6种等氮、等能的试验饲料投喂凡纳滨对虾(6.328±0.630 g),以鱼粉含量为25 %的饲料为对照组(A)。饲养7 d后开始收集粪便,测定凡纳滨对虾对饲料的表观消化率。养殖试验结束后,研究酵母提取物替代鱼粉对凡纳滨对虾消化酶的影响。试验结果:凡纳滨对虾对各组饲料均具有较高的干物质表观消化率(77.96 %~81.21 %)和粗蛋白表观消化率(87.19 %~92.82 %)；各替代组饲料的表观消化率均高于对照组,其中C、E和F组的干物质表观消化率显著高于对照组(P<0.05),粗蛋白表观消化率随酵母提取物用量的增加而显著增加(P<0.05)；凡纳滨对虾肝胰腺中类胰蛋白酶的活性随饲料中酵母提取物用量的增加而显著升高(P<0.05),脂肪酶的活性随饲料中酵母提取物用量的增加而显著降低(P<0.05)；肝胰腺中淀粉酶活性最高的为C组；各替代组凡纳滨对虾的肠胰蛋白酶活性均高于对照组。结果表明,以氨基酸平衡酵母提取物替代饲料中的鱼粉可以提高凡纳滨对虾对饲料的消化机能。     

酵母培养物和芽孢杆菌对凡纳滨对虾生长、蛋白酶活性和免疫性能的影响

研究了饲料中添加酵母培养物(益康XP)和芽孢杆菌(Bacillus)制剂对凡纳滨对虾(Litopenaeusvannamei)生长、肌肉成分、蛋白酶活性和免疫功能的影响。在基础饲料(对照组)中分别添加0.075%益康XP、0.100%益康XP、0.200%芽孢杆菌,饲养均重(5.57±0.21)g的凡纳滨对虾45 d。结果表明,添加0.075%益康XP、0.100%益康XP、0.200%芽孢杆菌分别提高凡纳滨对虾增重率17.24%、12.29%、20.18%,降低饲料系数14.28%、9.77%、12.03%,提高蛋白质效率16.49%、10.05%、12.98%(P<0.05);添加酵母培养物和芽孢杆菌对凡纳滨对虾肌肉组成成分没有影响(P>0.05);0.075%益康XP组、0.100%益康XP组、0.200%芽孢杆菌组肝胰脏蛋白酶活性较对照组分别提高25.24%、15.22%、54.92%(P<0.05);各试验组肠蛋白酶活性与对照组相比有所提高,但均未达到显著水平(P>0.05);0.100%益康XP、0.200%芽孢杆菌组凡纳滨对虾血清酚氧化酶活性、溶菌酶活性和超氧化物歧化酶活性均显著高于对照组(P<0.05);攻毒实验表明,感染溶藻弧菌后,芽孢杆菌组对虾第1、3、4天的累积死亡率均显著低于对照组(P<0.05),第4天时的免疫保护率达到27.1%,而添加益康XP对累积死亡率无显著影响(P>0.05)。综上所述,饲料中添加酵母培养物益康XP和芽孢杆菌均能改善凡纳滨对虾生长性能和消化功能,芽孢杆菌能增强凡纳滨对虾对溶藻弧菌的抗感染功能。     

蝇蛆粉替代鱼粉对凡纳滨对虾生长的影响

为探讨凡纳滨对虾饲料中用蝇蛆粉替代鱼粉的可行性及适宜的添加比例,研究了蝇蛆粉替代饲料中部分鱼粉对凡纳滨对虾(Litopenaeus vannamei)生长、成活和饵料系数的影响。饲喂试验共持续了65 d。结果显示:当蝇蛆粉替代鱼粉添加量为7%时,试验中期(32 d)和末期对虾增重率(WGR)和特定生长率(SGR)均显著高于其他组(P<0.05)。在低于7%添加范围内,随着蝇蛆粉添加水平的增加对虾WGR和SGR逐渐提高,超过7%后,对虾WGR和SGR逐渐下降。试验中期和末期,17%添加组饵料系数均显著高于其余各组(P<0.05),7%添加组饵料系数略高于对照组但差异不显著。无论是中期还是末期,蝇蛆粉替代鱼粉对凡纳滨对虾的成活率未产生显著影响(P>0.05)。在凡纳滨对虾饲料中添加7%的蝇蛆粉替代鱼粉可促进对虾生长,利用蝇蛆粉替代对虾饲料中的部分鱼粉是可行的。     

低鱼粉饲料中添加羟基蛋氨酸硒对凡纳滨对虾生长性能、抗氧化能力和抗亚硝酸盐胁迫的影响

[目的]本实验旨在研究低鱼粉饲料 中添加羟基蛋氨酸硒(HMSe)对凡纳滨对虾(Litopenaeus vannamei)生长性能、抗氧化能力及抗亚硝酸盐胁迫的影响。[方法]实验选用初始体质量为(0.90±0.05)g的凡纳滨对虾,分别投喂HMSe添加水平为0.000、0.375、0.750、1.500和2.250 mg/kg的实验饲料,命名为HMSe0 、HMSe1、HMSe2、HMSe3和HMSe4,每组3个重复,养殖8周。养殖实验结束后,进行12 h 的亚硝酸盐胁迫实验。[结果]结果表明,凡纳滨对虾的终末体质量(FBW)、增重率(WG R)和饲料效率(FE)随着饲料中HMSe水平的增加呈现先升高后下降的趋势,并在HMSe2组达到峰值。随着饲料中HMSe水平的提高,对虾全体和肌肉中的硒含量均显著增加,而全虾粗蛋白和粗脂肪的含量呈现先升高后降低的趋势,并分别在HMSe2组和HMSe1组达到最大值。HMSe4组中凡纳滨对虾的血清谷胱甘肽过氧化物酶(GSH-Px)和肝胰腺过氧化氢酶(CAT)活性显著高于HMSe0组。亚硝酸盐胁迫显著影响凡纳滨对虾的存活率。与胁迫前比较,胁迫后对虾肝胰腺中MDA含量升高,GST、CAT和T-SOD的活性降低,而补充适量的HMSe可减轻这些负面影响。根据凡纳滨对虾胁迫后成活率的二次多项式回归分析,低鱼粉饲料中凡纳滨对虾的HMSe最适添加量为1.350 mg/kg。[结论]综上所述,在低鱼粉饲料中添加0.750~1.350 mg/kg HMSe,能够提高凡纳滨对虾的生长性能、饲料利用率和抗亚硝酸盐胁迫的能力。     

鲜活蝇蛆对凡纳滨对虾生长和免疫的影响

用等质量的蝇蛆(按湿质量计)逐级替代对虾人工配合饲料,研究对凡纳滨对虾生长性能、肌肉营养成分及免疫参数的影响.试验分为5组(A～E),以凡纳滨对虾商品饲料A作为对照组,B、C、D、E分别替代A饲料总量的25%、50%、75%、100%.每组设2个重复,每个重复放养平均质量3.8 g的凡纳滨对虾50尾,养殖42 d.试验结果表明,B、C、D组凡纳滨对虾的体质量、体长、特定生长率与对照组差异不显著(P>0.05),E组与对照组差异显著(P<0.05).肌肉蛋白质、脂肪、灰分各组间差异不显著(P>0.05),E组水分显著高于其他组(P<0.05).各处理间红细胞密度无显著差异(P>0.05).酸性磷酸酶(ACP)和碱性磷酸酶(AKP)活性随着鲜活蝇蛆比重增加呈逐渐下降态势,E组ACP与对照组差异显著(P<0.05),其他处理组与对照组间差异不显著(P>0.05);除B组AKP与对照组无显著差异外(P>0.05),其他处理组与对照组间差异显著(P<0.05).在本试验条件下,用少量鲜活蝇蛆替代对虾配合饲料是可行的.     

饲料添加益生菌对凡纳滨对虾肠道菌群、Toll受体及溶菌酶基因表达及抗感染的影响

以初体重为(7.20±1.38)g的凡纳滨对虾(Litopenaeus vannamei)为研究对象,在室内养殖箱进行3周的养殖实验和2周的哈维氏弧菌(Vibrio harveyi)人工感染实验,其中对照组每日投喂普通商品饲料,实验组每日投喂在普通商品饲料中添加地衣芽孢杆菌(Bacillus licheniformis)1.0×10~8 CFU/m L配制成的实验饲料。目的是研究饲料中添加益生菌对凡纳滨对虾肠道菌群、Toll受体及溶菌酶基因表达量和抗哈维氏弧菌能力的影响。实验结果表明,在饲料中添加地衣芽孢杆菌可显著提高对虾抗哈维氏弧菌感染的能力,其相对免疫保护率为22.22%。与对照组相比,实验组可显著降低对虾肠道内弧菌数量(P0.05)。感染哈维氏弧菌后,实验组溶菌酶(lysozyme,LZM)m RNA的相对表达量在12 h、18 h、24 h、36 h、48 h、72 h均显著高于对照组(P0.05)。实验组感染哈维氏弧菌后在6 h、12 h、18 h、24 h、36 h、48 h、72 h、7 d的Toll受体(Toll receptor)m RNA的相对表达量均显著高于对照组(P0.05)。实验结果提示:饲料中添加地衣芽孢杆菌可有效提高对虾抗哈维氏弧菌感染的能力,这种能力的提高可能是通过降低对虾肠道内的弧菌量,并提高抗病相关基因的表达量实现的。     

饲料中花生四烯酸水平对凡纳滨对虾免疫相关基因表达及抗菌能力的影响

为了评估饲料中花生四烯酸(arachidonic acid,ARA)水平对凡纳滨对虾免疫相关基因表达及抗菌能力的影响,分别以鱼油和混合植物油为脂肪源,设计了2个系列共9组不同ARA含量的等氮等能,且具备相同饱和脂肪酸(SFA)、单不饱和脂肪酸(MUFA)、多不饱和脂肪酸(PUFA)和n-3/n-6比例的实验饲料,投喂对虾6周后,检测各组对虾在急性感染溶藻弧菌0、24、36和42 h时鳃组织中Toll受体、IMD(immune deficiency)和溶菌酶m RNA表达量,并统计感染后96 h内对虾的死亡情况。结果表明:1对虾摄食以鱼油为脂肪源的饲料[饲料DHA(22:6n-3)和EPA(20:5n-3)含量分别为5.85和3.83 mg/g饲料],其鳃组织中Toll受体、IMD和溶菌酶m RNA表达量均随饲料中ARA含量的升高呈现先升高后下降的变化;0.56(B组)和0.87 mg ARA/g饲料组(C组)对虾溶菌酶m RNA表达量显著高于0.44(A组)、1.02(D组)和0.28 mg ARA/g饲料组(E组)(P0.05);对虾摄食以植物混合油为脂肪源的饲料(DHA和EPA含量分别为3.28和1.87 mg/g饲料),其鳃组织中Toll受体、IMD和溶菌酶m RNA表达量随饲料中ARA含量的升高而升高;1.44 mg ARA/g饲料组(I组)对虾Toll受体m RNA表达量显著高于0.19 mg ARA/g饲料组(F组)(P0.05)。2人工急性感染溶藻弧菌后,各组对虾鳃组织中Toll受体、IMD和溶菌酶m RNA的表达量随感染进程均出现显著变化。摄食以鱼油为脂肪源的饲料时,对虾鳃组织中Toll受体、IMD和溶菌酶m RNA表达量峰值均出现在0.56 mg ARA/g饲料组(B组),且峰值分别出现在感染后24、42和24 h。摄食以混合植物油为脂肪源的饲料时,对虾鳃组织中Toll受体、IMD和溶菌酶m RNA表达量峰值均出现在1.44 mg ARA/g饲料组(I组),且峰值分别出现在感染后24、42和36 h。3各实验组对虾急性感染溶藻弧菌后96 h累积死亡率无显著差异。本研究表明,饲料ARA水平影响凡纳滨对虾免疫相关基因(Toll受体、IMD和溶菌酶)的表达,且ARA调控免疫基因表达的效果受饲料EPA和DHA水平的影响。     

蝇蛆粉和β-葡聚糖对凡纳滨对虾生长和免疫的影响

设计了5种等氮、等能的实验饲料(D1～D5)以评定添加蝇蛆粉和β-葡聚糖对凡纳滨对虾生长和免疫力的影响。以实用饲料D1作为对照组,D2和D3是在D1的基础上,分别以5%和3%的蝇蛆粉替代鱼粉,D4和D5是在D1的基础上,分别以0.5%和1%的β-葡聚糖产品(含β-1,3-葡聚糖25%)替代面粉。用上述5种饲料进行了一个为期8周的养殖试验。每种饲料处理设置3个重复,每个重复放养了体长为1.5 cm的幼虾60尾。每个重复被置于一个大小为33 cm×80 cm×100 cm的网箱中养殖,网箱被放置于一个12 m~3水体的室内循环水池中随机编组。试验期间每天投喂饲料4次,为表观饱食投喂。养殖试验结束后,计算成活率、增重和饲料系数,分别从每箱中抽取部分虾的血液进行血清中非特异性免疫指标和生化成分指标的分析,还分别从每箱中抽取部分虾以溶藻胶弧菌作攻毒试验。饲养试验的结果显示,各处理间的成活率、增重和饲料系数的差异不显著(P>0.05)。各处理间的血清酚氧化酶存在显著性差异(P<0.05),但不具有规律性。各处理间的血清超氧化物歧化酶活性的差异不显著(P>0.05)。D1组虾的血清溶菌酶活力显著地高于其它各组(P<0.05)。D1组虾血清的谷丙转氨酶和乳酸脱氢酶指标显著地高于其它各组(P<0.05)。D1组在攻毒后的前2 d的累计死亡率极显著地高于其它各组(P<0.01)。4 d后各组的死亡率均趋于稳定。D1组的最终死亡率(53.3%)显著高于D2组的最终死亡率(33.3%)和D5组的最终死亡率(37.8%) (P<0.05)。结果表明,在凡纳滨对虾的饲料中添加蝇蛆粉和β-葡聚糖能在一定程度上提高凡纳滨对虾抵抗弧菌的能力,但对生长和饲料效率没有正面影响。     

抗菌肽对凡纳滨对虾生长和血清非特异性免疫指标的影响

为考察抗菌肽对凡纳滨对虾(Litopenaeus vannamei)生长、饲料利用和免疫能力的影响,分别在基础组饲料中添加0 mg/kg(对照组)、300 mg/kg、400 mg/kg和500 mg/kg抗菌肽,投喂平均体重为(0.8±0.1 g)的凡纳滨对虾6周。结果表明,饲料中添加抗菌肽后,凡纳滨对虾的成活率均显著高于对照组(P<0.05);300 mg/kg抗菌肽组的增重率和饲料系数分别为509.10%、1.33,较对照组提高增重率8.76%(P<0.05),降低饲料系数12.5%(P<0.05),而添加400 mg/kg、500 mg/kg抗菌肽对增重率、饲料系数无显著影响,但显著提高了肌肉粗脂肪含量,各处理组在肌肉粗蛋白、水分含量上无显著差异;300 mg/kg、400 mg/kg抗菌肽组的血清碱性磷酸酶、超氧化物歧化酶、谷丙转氨酶、谷草转氨酶及400 mg/kg抗菌肽组的溶菌酶均显著高于对照组。上述研究表明,饲料中添加300 mg/kg抗菌肽,可显著提高凡纳滨对虾成活率和增重率,降低饲料系数;添加400 mg/kg抗菌肽,对血清非特异性免疫指标有提高作用,凡纳滨对虾饲料中抗菌肽的添加量建议为300～400 mg/kg。     

发酵豆粕替代鱼粉对凡纳滨对虾生长、免疫相关酶及免疫相关基因表达的影响

从免疫相关酶活及基因转录水平角度探讨发酵豆粕替代鱼粉对凡纳滨对虾健康生长及免疫机能机制的影响。实验设置5种实用饲料,以30%鱼粉组(FM)为对照组,分别用4%(FSM4)、8%(FSM8)、12%(FSM12)和16%(FSM16)的发酵豆粕,替代9.7%、19.4%、29.1%和38.8%鱼粉,分为4个处理组,饲养体质量为(7.62±0.23)g的凡纳滨对虾60 d后,统计生长性能,检测肌肉营养成分、血清及肝胰腺免疫相关酶活性,肝胰腺HSP70和鳃Toll受体、IMD、溶菌酶(LZM)免疫相关基因m RNA的表达水平。结果显示:(1)与对照组相比,发酵豆粕替代鱼粉对凡纳滨对虾成活率无显著影响;过低或过高水平的发酵豆粕替代鱼粉皆会影响凡纳滨对虾的特定生长率。(2)除FSM12组外,肌肉粗蛋白含量发酵豆粕替代组均低于对照组;粗脂肪含量随着发酵豆粕替代量的升高而降低,FSM16组最低。(3)血清谷丙转氨酶活FSM4和FSM16组显著高于对照组;谷草转氨酶活FSM4组最高,而FSM8组最低;除FSM12组外;碱性磷酸酶活性发酵豆粕替代组显著高于对照组;除FSM16组外,血清总蛋白与肝胰腺丙二醛含量发酵豆粕替代组与对照组无显著性差异。(4)随着发酵豆粕替代量增加,鳃Toll受体m RNA表达呈上升趋势,鳃IMD m RNA表达则呈先升后降趋势,发酵豆粕替代比例过高会降低鳃LZM m RNA表达水平,而肝胰腺HSP70 m RNA表达量则随着发酵豆粕替代比例增加呈上升趋势。综上所述,发酵豆粕适量替代鱼粉对凡纳滨对虾生长性能无显著影响,并可提高免疫相关酶活,改变免疫相关基因的表达。本实验条件下适宜发酵豆粕用量为8%~12%;替代量过高,会引起机体的过度应激。     

发酵豆粕部分替代鱼粉后凡纳滨对虾对赖氨酸的需求量

为研究发酵豆粕部分替代鱼粉后,饲料赖氨酸(Lys)水平对凡纳滨对虾生长、体组成与血清生化指标的影响,进而确定凡纳滨对虾对饲料赖氨酸的需要量,实验在基础饲料中分别添加0%、0.25%、0.50%、0.75%和1.00%的晶体赖氨酸配制成5种等氮等脂的实验饲料(含粗蛋白41.5%、粗脂肪7.5%),实测各组赖氨酸含量分别为2.43%、2.65%、2.87%、3.06%和3.24%,记为Lys0、Lys25、Lys50、Lys75和Lys100。选择初始体质量为(2.0±0.1) g的凡纳滨对虾随机分为5组,每组3个重复,每个重复50尾虾,在室内水泥池中进行为期56 d的养殖实验。结果显示,随着饲料赖氨酸水平的提高,凡纳滨对虾的增重率(WGR)和特定生长率(SGR)先升高后降低,在Lys75组达到最高,且该组饲料系数(FCR)最低;凡纳滨对虾成活率不受饲料赖氨酸水平的影响。Lys75组对虾肌肉粗蛋白和粗脂肪含量最高,而对虾肌肉粗灰分和水分含量则不受饲料赖氨酸水平的影响;肌肉必需氨基酸中的赖氨酸、缬氨酸(Val)、异亮氨酸(Ile)、苯丙氨酸(Phe)随着饲料赖氨酸水平的提高呈先升高后降低的趋势。随着饲料赖氨酸水平的提高,血清中谷丙转氨酶(ALT)、谷草转氨酶(AST)活性呈先升高后降低的趋势,甘油三酯(TG)含量呈逐渐升高的趋势,Lys75组超氧化物歧化酶(SOD)活性显著低于其他各组。对SGR、FCR与饲料赖氨酸水平进行二次曲线拟合分析,结果显示,凡纳滨对虾对赖氨酸的最适需求量分别为2.88%(饲料粗蛋白的6.94%)、2.89%(饲料粗蛋白的6.96%)。本实验通过探讨凡纳滨对虾在该饲料配方条件下对赖氨酸的最适需求量,旨在为其大规模配合饲料的生产提供参考。     

转vp28蓝藻口服剂对凡纳滨对虾抗白斑综合征病毒能力及免疫反应的影响

为探讨转vp28蓝藻(Anabaena sp.PCC7120)口服剂对凡纳滨对虾抗白斑综合征病毒能力及其相应的免疫反应,本研究将此口服剂免疫幼虾7 d,再分别通过投喂攻毒和浸泡攻毒,测定其存活率及相应的免疫指标。投喂攻毒和浸泡攻毒的实验组存活率分别为78.8%和83.19%,表明该口服剂能显著增强对虾抗白斑综合征病毒的能力。蓝藻口服剂免疫对虾的酶活性检测结果显示,超氧化物歧化酶(SOD)、酚氧化酶(PO)、过氧化氢酶(CAT)和碱性磷酸酶(AKP)活性在免疫后2 h均有上升趋势,且在48或96 h达到最高值,这表明该口服剂能引起对虾体内酶活性变化。投喂攻毒的对虾酶活性检测结果显示,实验组攻毒后的对虾肝胰腺SOD活性分别比阳性对照组、野生型组、空载体组显著提高42.10%、32.26%和16.04%,且攻毒后的肌肉SOD活性分别比阴性对照组、阳性对照组、野生型组和空载体组略微提高17.70%、11.50%、15.00%以及10.00%。实验组攻毒后的对虾肝胰腺PO、CAT和AKP活性比阳性对照组分别提高12.17%、88.80%和240.07%,比野生型组分别提高21.49%、30.90%和100%;酸性磷酸酶(ACP)活性比阴性对照组略微提高,而在肌肉中各组ACP活性无显著性差异。同时浸泡攻毒组结果与投喂攻毒组具有类似的趋势。浸泡攻毒的实验组CAT和AKP活性显著高于其余处理组,且CAT活性比投喂攻毒更为显著。浸泡攻毒的实验组肝胰腺PO活性显著高于阳性对照组、野生型组和空载体组,而各组肌肉ACP活性无显著性差异。研究表明,转vp28蓝藻口服剂能够增强凡纳滨对虾抗病能力并延缓对虾死亡。转vp28蓝藻PCC7120本身可作为幼虾饵料直接投喂,无需提取纯化,有望大规模应用于对虾养殖产业。     

Use of new soybean varieties in practical diets for the Pacific white shrimp,Litopenaeus vannamei

This study was designed to evaluate the efficacy of eight sources (designated A–H) of soybean meal (SBM) which included six new non‐genetically modified soya varieties in practical feed formulation for Pacific white shrimp, Litopenaeus vannamei, using both growth and digestibility trials. A soybean meal‐based reference diet was formulated using conventional soybean meal (527 g kg^?1 diet), which was then replaced on an isonitrogenous basis with various other experimental soybean meals. In a 6‐week growth trial, shrimp in four replicate tanks per dietary treatment (10 shrimp per tank, initial weight 0.52 ± 0.04 g) were cultured in a recirculating system. There were no significant differences with respects to per cent weight gain and survival across all dietary treatments; however, final weights and feed conversion ratio (FCR) were lower in shrimp offered diet 3. Apparent digestibility coefficients for the eight (A–H) different soybean meals were determined in L. vannamei for dry matter (ADMD), gross energy (ADE) and crude protein (ADP) using 10 g kg^?1 chromic oxide as inert marker with 70 : 30 replacement techniques. Coefficients ranged from 71.3% to 88.3%, from 76.6% to 91.3% and from 93.6% to 99.8%, for ADMD, ADE and ADP, respectively. Improved digestibility values were observed in soybean C which was characterized by crude protein (471 g kg^?1), crude fat (97 g kg^?1), low cooking temperature (180 °C), higher nitrogen solubility index (689 g kg^?1) and protein dispersibility index (619 g kg^?1). This indicates that new lines of soybean meal can be used to improve digestibility coefficients in shrimp feeds.     

Effects of water hyacinth (Eichhornia crassipes) leaf protein concentrate as soybean protein replacement in white shrimp Litopenaeus vannamei (Boone) postlarvae diet

The potential of water hyacinth leaf protein concentrate (WHLPC) as an alternative protein source to soybean meal in formulated diets for the white shrimp Litopenaeus vannamei (Boone) postlarvae, was assessed. Isonitrogenous and isolipidic diets were formulated containing 40% protein and 8% lipid. WHLPC replaced 0%, 25%, 50% and 75% of soybean meal protein in the formulated diets. Twenty postlarval Litopenaeus vannamei weighing 5.0 ± 0.00032 mg were randomly assigned to twelve 30‐L aquarium tanks and were fed experimental diets for 70 days. Results show that the overall biological performance of shrimp in terms of specific growth rate (SGR), protein efficiency ratio (PER), feed efficiency (FE) and survival in treatment receiving the 25% WHLPC replacement is comparable to that of the control diet. Replacement levels beyond 25% exhibited significant depression in terms of growth performance of the shrimp. Collectively, these findings indicate that WHLPC can replace 25% of soybean meal protein in the formulated diets of L. vannamei.     

Substitution of fish meal by Jatropha curcas kernel meal: Effects on growth performance and body composition of white leg shrimp (Litopenaeus vannamei)

Jatropha curcas (L.) is a multipurpose and drought‐resistant tree, widespread throughout the tropics and subtropics. Its seeds are rich in oil and protein (contains 600–660 g kg^?1 crude protein similar to fish meal). It is being promoted as a biofuel plant. Jatropha kernel meal obtained after oil extraction is an excellent source of protein. However, presence of toxic and antinutritional constituents restricts its use in fish and shrimp feed. An 8‐week experiment was conducted to evaluate the nutritional quality of the detoxified Jatropha kernel meal (DJKM) in white leg shrimp (Litopenaeus vannamei). Shrimp (60) with an initial average body weight of 4.46 ± 0.64 g were randomly distributed into three treatments with four replicates and fed isonitrogenous and isoenergetic diets (crude protein 350 g kg^?1, crude lipid 90 g kg^?1): Control (fish meal‐based protein), JC₂₅ and JC₅₀ (25% and 50% of fish meal protein replaced by DJKM). Higher (P < 0.05) body mass gain, specific growth rate and metabolic growth rate were observed in DJKM‐fed groups than in Control group. However, lower (P > 0.05) feed conversion ratio was observed in DJKM‐fed groups, while protein efficiency ratio exhibited an opposite trend. Protein, ash and gross energy content of the whole shrimp body were higher (P < 0.05) in DJKM‐fed groups compared to Control group. Moisture and lipid content of the whole shrimp body did not differ significantly among the three groups. Cholesterol level in plasma was highest (P < 0.05) in the Control group, followed by JC₂₅ and JC₅₀ groups; all being significantly different. In conclusion, DJKM is a promising fish meal replacer in shrimp diets.     

Effect of lignite fulvic acid on growth,antioxidant ability,and HSP70 of Pacific white shrimp, <Emphasis Type="Italic">Litopenaeus vannamei</Emphasis>

This study was conducted to evaluate the effects of fulvic acid (0, 0.3, 0.6, 0.9, and 1.2%) as feed additive on growth, feed utilization, antioxidant ability, and HSP70 in hemolymph and hepatopancreas of juvenile white shrimp Litopenaeus vannamei (average weight 2.5 g) reared under experiment conditions. Shrimp were stocked at a density of 625 shrimps m^?3 for 60 days in net cages submerged in recirculating tanks. At the end of the experiment, specific growth rates and survival rates of shrimp in treatment groups fed with 0.6, 0.9, and 1.2% fulvic acid were higher compared to that of the control group. Shrimp fed 0.6, 0.9, and 1.2% fulvic acid had significantly lower feed conversion rates than those fed control diet. The optimum dietary fulvic acid requirement for juvenile shrimp based on weight gain was 0.897%. Furthermore, superoxide dismutase activity and peroxidase activity increased significantly, while malonaldehyde content decreased in the hemolymph and hepatopancreas of shrimp fed 0.9 and 1.2% dietary fulvic acid. Glutathione content increased obviously in hemolymph of shrimp fed 0.6, 0.9, and 1.2% fulvic acid. In hepatopancreas, glutathione content was significantly higher in shrimp supplemented with 1.2% fulvic acid. HSP70 decreased obviously in hemolymph of shrimp fed 0.9 and 1.2% fulvic acid, while shrimp fed with 0.6 and 0.9% fulvic acid showed lower HSP70 level in hepatopancreas. The results of this study demonstrated that dietary fulvic acid could improve survival rates, growth, feed utilization, antioxidant capability, and stress resistance of juvenile L. vannamei reared under intensive stocking conditions.     

Effects of freeze‐dried powder of the Antarctic krill Euphausia superba on the growth performance,molting and fatty acid composition of the Pacific white shrimp Litopenaeus vannamei

This study was designed to evaluate the effect of dietary replacement fish meal supplemented with freeze‐dried powder of the Antarctic krill Euphausia superba (FDPE) on the growth performance, molting, and fatty acid composition of the Pacific white shrimp Litopenaeus vannamei (initial weight 1.27 ± 0.09 g). Four diets containing 0% (S0 group), 10% (S10 group), 20% (S20 group), and 30% (S20 group) FDPE were used in the present study. At the end of growth trial, the final body weight, weight gain rate, and specific growth rate in the S10, S20, and S30 groups were higher than those in the S0 group. The shrimp in the S10 and S20 groups exhibited better molting synchronism than those in the S0 group. The astaxanthin content in the hepatopancreas from the shrimp in the groups supplemented with FDPE was significantly higher than that in the S0 group (p < 0.05) and increased as the FDPE content in the feed increased. The shrimp in the S10, S20, and S30 groups had a higher monounsaturated fatty acid (MUFA) content in the hepatopancreas than those in the S0 group. The sum of EPA and DHA in the muscles from the shrimp in the S0 group was lower than that in the other groups. These results indicate that the dietary inclusion of 10%–20% FDPE can be used as practical diets in L. vannamei farmed under a clear water system.     

The use of HUFA-rich algal meals in diets for Litopenaeus vannamei

A 15‐week growth trial was conducted with juvenile, Pacific white shrimp Litopenaeus vannamei to study the efficacy of using algal meals as a source of highly unsaturated fatty acids in practical diets that are designed to contain no marine protein or oil sources. Based on previous study, a practical diet was designed containing co‐extruded soybean poultry by‐product meal with egg supplement and soybean meal as the primary protein sources for formulations containing 350 g kg^?1 crude protein and 100 g kg^?1 lipid. To further refine the diets, the fish oil in two of the diets was completely substituted with plant oils and oil originating from microbial fermentation products rich in docosahexanoic acid (DHA) and arachidonic acid (ArA). A commercial shrimp feed was also included in the trial for comparison. The mean values for shrimp final weight (17.8 g), yield (537.7 g m^?2 or 703.2 g m^?3), survival (98.5%) and feed conversion ratio (1.4 : 1) showed no statistically significant differences between diets. The results suggest that co‐extruded soybean poultry by‐product meal and oil from heterotrophic microalgal fermentation sources can be potential candidates for fish meal and marine oil replacement in shrimp diets.     

亚硝态氮胁迫下凡纳滨对虾体内亚硝态氮的积累与能量代谢响应

为探究亚硝态氮胁迫下凡纳滨对虾[体长为(6.8±0.3) cm,体质量为(4.0±0.6) g]体内亚硝态氮的时空分布与能量代谢相关酶活性的响应,实验设置0(对照组)、0.8、4.0和8.0 mmol/L 4个处理组,进行持续96 h的亚硝态氮胁迫实验和12 h的恢复实验。结果显示,凡纳滨对虾死亡率与胁迫浓度呈现显著的正相关性。胁迫6 h内,亚硝态氮在凡纳滨对虾鳃、血淋巴、肠道、肝胰腺和肌肉组织中明显积累,且积累量与胁迫浓度呈现正相关。相同胁迫浓度组,亚硝态氮在对虾鳃中积累最多,肌肉中最少,鳃中的积累量约为肌肉的3倍。Na⁺-K⁺-ATP酶活性在0.8和4.0 mmol/L组对虾肝胰腺和肌肉中显著升高,而在8.0 mmol/L组的肌肉中显著降低。胁迫各组对虾肝胰腺AMPK活性显著上升,且与胁迫浓度呈现正相关性。恢复期间,除血淋巴(8.0 mmol/L组)外,各组织中亚硝态氮1 h恢复效率均超过50%,且肝胰腺和鳃的恢复效率最高,达到74%以上。血淋巴、鳃、肠道中亚硝态氮恢复到对照组水平的时间最短,均在6 h以内,而水体中亚硝态氮含量显著升高。...