鸡肉粉完全替代鱼粉饲料中补充包被氨基酸对凡纳滨对虾生长、体成分及组织氨基酸含量的影响

为了探讨鸡肉粉完全替代鱼粉时饲料氨基酸的平衡性以及外源氨基酸的添加方式与凡纳滨对虾生长、体成分、血浆游离氨基酸及肌肉氨基酸含量的关系, 本试验采用26因子试验设计进行了为期56d的饲养试验。2个饲料蛋白质水平分别为40%和32%, 6个饲料处理分别为鱼粉组(对照组)、鸡肉粉组、鸡肉粉+晶体EAA组、鸡肉粉+晶体EAA+晶体NEAA组、鸡肉粉+包被EAA组、鸡肉粉+包被EAA+包被NEAA组, 配制12组饲料。将凡纳滨对虾(0.300.01) g随机分配到36个圆桶(150 L)中, 每桶30尾, 每3个桶为一个处理组, 饲喂一种饲料, 每天饱食投喂三次。在每一饲料蛋白质水平下, 无论是补充晶体氨基酸(CAA)组还是包被氨基酸组对虾的增重率均显著高于鸡肉粉组(P0.05), 且在32%蛋白质水平下, 包被EAA组对虾增重率达到了鱼粉组水平(P0.05); 补充晶体EAA+NEAA组对虾增重率与补充晶体EAA组无差异(P0.05), 但均显著低于补充包被氨基酸组(P0.05); 补充包被EAA组对虾增重率显著高于补充包被EAA+NEAA组(P0.05)。饲料系数的变化正好与增重率变化相反(P0.05)。饲喂高蛋白质水平饲料较之饲喂低蛋白质饲料明显提高对虾增重率、虾体蛋白含量(P0.05), 但降低虾体脂肪含量(P0.05)。包被氨基酸组凡纳滨对虾血浆游离氨基酸含量总体显著低于CAA组(P0.05)。除谷氨酸、甘氨酸以及脯氨酸外, 各组对虾肌肉氨基酸含量无显著差异(P0.05)。结果表明, 在32%饲料蛋白质水平下, 用鸡肉粉完全替代鱼粉时, 饲料中补充包被EAA可明显促进凡纳滨对虾的生长, 且达到了鱼粉组的饲喂效果。     

盐度对哈氏仿对虾肌肉一般营养成分和氨基酸组成及含量的影响

通过调查不同盐度(12～36)环境下养殖的哈氏仿对虾(Parapenaeopsis hardwickii)肌肉一般营养成分和氨基酸组成及含量,研究了盐度对该虾肌肉营养品质的影响。结果显示,肌肉的水分随环境盐度升高出现显著的直线下降,而粗蛋白含量随环境盐度升高而直线升高;各盐度组的粗脂肪含量虽然没有明显差异,但其含量随盐度升高有一定的线性下降趋势;36盐度组的粗灰分含量比12、16、20和28盐度组的明显高,32盐度组的灰分含量比20和24盐度组的也明显高;所检测的肌肉干样16种氨基酸中,只有3种氨基酸的含量随盐度升高而升高,而其他13种氨基酸的含量随盐度升高明显降低,其中有10种氨基酸的含量在盐度12～24条件下的比盐度28～36条件下的明显高,而这些氨基酸含量在盐度12～24之间没有明显差异。各盐度组间氨基酸总量和鲜味氨基酸含量均没有明显差异;必需氨基酸和半必需氨基酸含量在盐度12～24条件下的均比盐度28～36条件下的明显高,而在12～24盐度组之间以及28～36盐度组之间均没有明显差异。必需氨基酸/氨基酸总量的比值和必需氨基酸/非必需氨基酸比值随盐度升高均明显线性降低;盐度12～24组的必需氨基酸指数(66.13～67.42)高于盐度28～36组的(62.56～64.46)。综上所述,盐度12～24环境下养殖的哈氏仿对虾肌肉营养价值相对较高,表现为低盐趋向,考虑到肌肉的水分含量和生长性能,哈氏仿对虾在养殖期间选择16～24盐度范围比较合适,同时也说明哈氏仿对虾适合大多数沿海地区环境的盐度条件。     

紫黑翼蚌钩介幼虫在不同规格寄主鱼寄生效果及对寄主鱼营养指标的影响

为提高紫黑翼蚌(Potamilus alatus)繁殖效率,探讨寄生对淡水石首鱼(Aplodinotus grunniens)营养指标的影响,实验通过比较钩介幼虫脱落数量,测试了不同规格寄主鱼的寄生效果,分析了寄生对寄主鱼血清生化指标及肌肉中氨基酸、脂肪酸含量的变化。结果显示:大规格组每尾鱼脱落数显著高于小规格组(P<0.05),小规格组每千克寄生鱼平均脱落稚贝数显著高于大规格组(P<0.05);寄生导致肌肉中肌酐显著升高(P<0.05),谷丙转氨酶、谷草转氨酶和乳酸脱氢酶显著降低(P<0.05),血糖、总蛋白、白蛋白、甘油三酯、总胆固醇、高密度脂蛋白和低密度脂蛋白与对照组无显著性差异(P>0.05);寄生组灰分与对照组无显著性差异(P>0.05),寄生组肌肉水分和粗脂肪含量显著高于对照组(P<0.05),粗蛋白显著低于对照组(P<0.05);寄生组天冬氨酸、丙氨酸、谷氨酸、酪氨酸、甘氨酸和精氨酸含量显著低于对照组(P<0.05),非必需氨基酸含量显著低于对照组(P<0.05),其他氨基酸之间无显著性差异(P>0.05)...     

黑水虻幼虫粉对凡纳滨对虾生长、免疫和脂质代谢的影响

试验旨在研究黑水虻Hermetia illucens幼虫粉替代鱼粉对凡纳滨对虾Litopenaeus vannamei生长性能、非特异性免疫和脂质代谢的影响。以黑水虻幼虫粉分别替代对照组饲料(FM)中10%(BSF10)、20%(BSF20)和30%(BSF30)的鱼粉蛋白质,共配制为四组等氮等脂的实验饲料,饲喂初始体质量为(0.88±0.01) g的凡纳滨对虾7周。结果显示, BSF10组和BSF20组对虾的生长性能与对照组相比无显著变化(P>0.05),但BSF30组对虾的生长性能显著降低(P<0.05)。与对照组相比, BSF20组和BSF30组对虾的全虾粗脂肪含量显著降低,BSF30组对虾血淋巴甘油三酯和总胆固醇水平显著降低(P<0.05),但肝胰腺粗脂肪水平无显著差异(P>0.05)。BSF10、BSF20和BSF30组对虾血淋巴谷丙转氨酶和谷草转氨酶活性显著低于对照组(P<0.05)。BSF10组对虾超氧化物歧化酶活性显著高于对照组, BSF20组对虾总抗氧化能力显著高于其余各组(P<0.05)。BSF30组对虾肝胰腺酸性磷酸酶和碱性磷酸...     

急性高渗胁迫对中华绒螯蟹雄蟹组织中可溶性蛋白质、血蓝蛋白、血糖与肝糖原含量的影响

实验以淡水(0.3‰)处理组为对照,研究了急性高渗胁迫(盐度16‰和30‰)对中华绒螯蟹(Eriocheirsinensis)雄蟹血淋巴和肝胰腺中可溶性蛋白质、血蓝蛋白、血糖及肝糖原含量的影响。结果显示,与对照组相比,进入16‰及30‰盐度后,蟹的血淋巴中可溶性蛋白质含量从6—48h显著降低(P<0.05),至72h时显著增加(P<0.05),而机体肝胰腺的可溶性蛋白质含量从12h开始至96h显著降低(P<0.05);血蓝蛋白含量在前24h显著降低(P<0.05),48h开始显著升高(P<0.05);肝糖原含量在6—96h与对照组相比有显著的降低(P<0.05);16‰盐度组蟹的血糖含量在24—48h时显著下降(P<0.05),到72h开始逐渐恢复(P>0.05),而30‰盐度组其血糖含量早在6—12h时就有显著的下降(P<0.05),到24h则开始逐渐升高。研究表明,在急性盐度胁迫下,糖类和蛋白质对中华绒螯蟹渗透压调节起重要的作用,其优先利用糖类的分解获得所需的能量,其中盐度越高,机体内葡萄糖的消耗越快,血糖水平的恢复也相应较快。对蛋白质的利用稍次之,机体可利用蛋白质的分解获得其渗透压调节的效应物游离氨基酸以维持渗透压平衡。     

饲料添加β-1,3-葡聚糖对凡纳滨对虾生长性能、血清代谢、免疫相关基因表达和抗亚硝酸氮应激能力的影响

实验旨在研究β-1,3-葡聚糖的不同投喂方式对凡纳滨对虾(Litopenaeus vannamei)生长、血清代谢和抗亚硝酸氮应激能力的影响。选用480尾初体重(0.43±0.01) g的凡纳滨对虾, 随机分为4组, 即G0(全程投喂基础饲料)、G1组(全程投喂0.1%β-1,3-葡聚糖饲料)、G2组(0.1% β-1,3-葡聚糖饲料7d+基础饲料7d循环)和G3组(0.1% β-1,3-葡聚糖饲料14d+基础饲料14d循环)。在养殖84d后, 应用亚硝酸钠进行120h亚硝酸氮应激实验。结果显示, 各实验组凡纳滨对虾生长性能和全虾营养成分没有显著性差异。在养殖84d后, G2和G3组凡纳滨对虾肝胰腺脂肪酶活性显著高于G0和G1组(P<0.05), G1、G2和G3组凡纳滨对虾血清胆固醇和甘油三酯含量显著高于G0组(P<0.05), G3组凡纳滨对虾肌肉脂多糖/?-1,3-葡聚糖结合蛋白(LGBP)、酚氧化物酶原(proPO)和超氧化物歧化酶(SOD)mRNA表达显著高于G0和G1组(P<0.05)。亚硝酸氮应激120h, G1、G2和G3组凡纳滨对虾累计死亡率显著低于G0组(P<0.05), G3组凡纳滨对虾累计死亡率显著低于G0、G1和G2组(P<0.05)。在亚硝酸氮应激120h后, 与G0组相比, G1、G2和G3组凡纳滨对虾血清总蛋白含量显著升高(P<0.05), 葡萄糖含量、谷丙转氨酶和谷草转氨酶活性显著降低(P<0.05); G3组凡纳滨对虾肌肉LGBP、proPO和SOD mRNA表达显著高于G0 (P<0.05), G1组凡纳滨对虾肌肉丝氨酸蛋白酶(SP)mRNA表达显著高于G0、G2和G3组(P<0.05)。结果表明, 14d间隔投喂0.1% β-1,3-葡聚糖可能通过促进能量代谢和LGBP、proPO和SOD mRNA表达提高凡纳滨对虾抗亚硝酸氮应激能力。     

不同形式蛋氨酸对黄鳝生长、血清生化、血清游离氨基酸含量及肌肉品质的影响

以初始体重(30.00±0.45) g的黄鳝(Monopterus albus)为研究对象, 以低鱼粉饲料为对照组, 在低鱼粉饲料中分别添加蛋氨酸有效含量为2 g/kg的晶体蛋氨酸(C-Met)、包膜蛋氨酸(E-Met)、蛋氨酸羟基类似物钙盐(MHA-Ca)、蛋氨酸羟基类似物(MHA), 研究其在低鱼粉黄鳝饲料中的利用效果, 共5个处理组, 养殖试验持续10周。结果表明: (1)在低鱼粉饲料中添加蛋氨酸均有提高黄鳝增重率和蛋白质效率比、降低饲料系数的趋势, 其中MHA-Ca和MHA组与对照组差异显著(P<0.05)。(2)在低鱼粉饲料中添加蛋氨酸均显著提高了肠道胰蛋白酶活力、血清胆汁酸、总胆固醇、总蛋白、尿素氮和血氨含量、肌肉黏附性与胶黏性(P<0.05); 添加MHA-Ca和MHA显著提高了肠道淀粉酶活力、血清葡萄糖和高密度脂蛋白胆固醇含量、肝脏谷草转氨酶活力、全鱼粗蛋白含量、肌肉硬度、弹性和咀嚼性(P<0.05), 显著降低了黄鳝肝体比与血清谷草转氨酶活力(P<0.05)。(3)对照组在摄食6h出现蛋氨酸吸收峰值, C-Met与MHA-Ca组均在摄食后9h出现蛋氨酸吸收峰值, E-Met组在摄食后12h出现蛋氨酸吸收峰值, MHA组分别在摄食后3h和9h出现蛋氨酸峰值。结果表明, 在低鱼粉饲料中添加蛋氨酸均能提高黄鳝生长和氨基酸代谢, 且MHA-Ca与MHA效果较佳。     

高盐胁迫对凡纳滨对虾消化及免疫相关酶活力的影响

为探讨高盐对凡纳滨对虾(Litopenaeus vannamei)消化及免疫相关酶活力的影响,实验设置了30、40、50、60共4个盐度梯度。对虾体长(7.84±0.68)cm,养殖密度333尾/m~3,每个梯度设3个平行,实验周期30d。取血淋巴、肌肉、肝胰腺等组织,检测其超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、碱性磷酸酶(AKP)和酸性磷酸酶(ACP)及蛋白酶、脂肪酶、淀粉酶活力。结果表明,盐度显著影响凡纳滨对虾肝胰脏中胃蛋白酶、脂肪酶、淀粉酶的活力(P0.05);随着盐度增加,消化相关酶活力均不断下降,处理间差异显著(P0.05);盐度对凡纳滨对虾不同组织的免疫指标产生影响,表现为随着盐度升高,血淋巴中,AKP活力逐渐升高,ACP、CAT和SOD活力均表现为先升高后降低;肌肉中,AKP、ACP和SOD活力呈现先升高后降低的变化趋势;肝胰脏中,AKP活力呈现先降低后升高再降低的变化趋势,ACP活力高盐处理间差异不显著(P0.05),CAT活力先降低后升高,SOD活力盐度40后逐渐降低。实验结果初步说明,高盐显著影响凡纳滨对虾的消化及免疫相关酶活力,且盐度对不同组织中免疫酶活力影响存在一定的组织特异性,50以上的高盐胁迫对对虾消化和免疫相关酶活力的影响尤为显著。     

盐度对日本囊对虾仔虾生长发育和Na+-K+-ATPase活力的影响

研究了盐度对日本囊对虾仔虾(Marsupenaeus Japonicus)的生长发育和Na -K -ATPase活力的影响。结果表明,盐度对日本囊对虾仔虾存活率、增重率和Na -K -ATPase活力的影响显著(P<0.05)。随着向低盐度变化的增加,仔虾的存活率和增重率明显下降,而向高盐度变化无显著差异;在盐度变化48h内,随着盐度变化的增加仔虾Na -K -ATPase活力变化增大,各处理组仔虾Na -K -ATPase活力随着取样时间的增加呈峰值变化,至24h时低盐度处理组酶活力达到最大值,而高盐度处理组达到最小值:至48h~72h时,不同盐度下仔虾Na -K -ATPase活力趋于稳定,而且盐度越低酶活力越大。由此表明日本囊对虾仔虾在低盐度地下卤水中的适宜盐度为20‰—24‰。     

不同家系凡纳滨对虾对低盐度的适应能力及其适应机理

为研究不同遗传背景的凡纳滨对虾(Litopenaeus vannamei)在对盐度的适应能力上具有明显的差异的机理, 比较了30个凡纳滨对虾家系在3个不同盐度水体(5‰、20‰和30‰)中饲养30d后的生长性状。研究结果证实了不同家系对虾在不同盐度条件下的生长性能和适应能力存在显著差异。研究进一步对比分析了各盐度条件下不同家系间生理代谢、ATP含量及ATP合成关键酶酶活力的差异, 并检测了不同家系凡纳滨对虾鳃Na+/K+-ATPase、Ca2+-ATPase酶活水平。结果发现盐度适应力差的对虾家系的Na+/K+-ATPase、Ca2+-ATPase酶活力较弱, 这可能是由于其机体能量供给不足所导致。此外, 研究以血浆中皮质醇浓度为指标, 对比了不同盐度下不同对虾家系的机体应激水平, 结果显示盐度适应力差的对虾家系在经30d饲养后仍处于应激状态。综合研究结果得出, 不同遗传背景的对虾对盐度的适应能力不同, 可能是由其机体代谢、离子转运及能量合成能力所决定。     

The Influence of water salinity on the free amino acid concentration in muscle and hepatopancreas of adult shrimps, Penaeus japonicus

Variations of the total free amino acid (FAA) pool and the content of specific amino acids have been measured in the muscle and hepatopancreas of adult shrimps, Penaeus japonicus, acclimatized at five water salinities: 38, 32, 26, 20 and 14%‰ The FAA content is always higher in muscle than in hepatopancreas at all tested salinites. On the other hand, the hepatopancreas exhibits the highest concentrations of essential amino acids. Two steps in the evolution of FAA content can be observed, the first one regarding decrease in salinity from 38 to 20%‰ and the second one, when salinity goes below 20%_°. The first step can be characterized by a 16% decrease of total FAA content in the muscle and a 36% increase in the hepatopancreas. In muscle, the variations are mainly due to changes in non-essential FAA content, whereas in the hepatopancreas, they are linked to variations in essential FAA content. The other step is characterized by a drastic increase in moisture and decrease in FAA content in both studied organs when water salinity is 14%‰ The total FAA content is about 40% lower in shrimps at 14%_° compared to 38%‰ seawater salinity. During adaptation, the FAA pool (mainly NEFAAs) of muscle seems to be directly related to osmoregulation, whereas in the hepatopancreas, its evolution seems to be linked with energy expenditure and protein synthesis. The results are evaluated in order to elucidate the role of FAA in intracellular osmoregulation and in relation to animal ecology.     

Branchial carbonic anhydrase activity and ninhydrin positive substances in the Pacific white shrimp, Litopenaeus vannamei, acclimated to low and high salinities

The Pacific white shrimp, Litopenaeus vannamei, acclimated to 30 ppt salinity, was transferred to either low (15 and 5 ppt), or high (45 ppt) salinity for 7 days. Hemolymph osmolality, branchial carbonic anhydrase activity, and total ninhydrin-positive substances (TNPS) in abdominal muscle were then measured for each condition. Hemolymph osmotic concentration was regulated slightly below ambient water osmolality in shrimp acclimated to 30 ppt. At 15 and 5 ppt, shrimp were strong hyper-osmotic regulators, maintaining hemolymph osmolality between 200 and 400 mOsm above ambient. Shrimp acclimated to 30 ppt and transferred to 45 ppt salinity were strong hypo-osmotic and hypo-ionic regulators, maintaining hemolymph osmolality over 400 mOsm below ambient. Branchial carbonic anhydrase (CA) activity was low (approximately 100 micromol CO(2) mg protein(-1) min(-1)) and uniform across all 8 gills in shrimp acclimated to 30 ppt, but CA activity increased in all gills after exposure to both low and high salinities. Anterior gills had the largest increases in CA activity, and levels of increase were approximately the same for low and high salinity exposure. Branchial CA induction appears to be functionally important in both hyper- and hypo-osmotic regulations of hemolymph osmotic concentrations. Abdominal muscle TNPS made up between 19 and 38% of the total intracellular osmotic concentration in shrimp acclimated to 5, 15, and 30 ppt. TNPS levels did not change across this salinity range, over which hemolymph osmotic concentrations were tightly regulated. At 45 ppt, hemolymph osmolality increased, and muscle TNPS also increased, presumably to counteract intracellular water loss and restore cell volume. L. vannamei appears to employ mechanisms of both extracellular osmoregulation and intracellular volume regulation as the basis of its euryhalinity.     

Metabolism and growth of juveniles of Litopenaeus vannamei: effect of salinity and dietary carbohydrate levels

The present study was designed to understand how carbohydrate (CBH) and protein metabolism are related in the penaeid shrimp Litopenaeus vannamei. With this information, we obtained a comprehensive schedule of the protein-carbohydrate metabolism including enzymatic, energetic, and functional aspects. We used salinity to determine its role as a modulator of the protein-carbohydrate metabolism in shrimp. Two experiments were designed. The first experiment evaluated the effect of CBH-salinity combinations in growth and survival, and hemolymph glucose, protein, and ammonia levels, digestive gland glycogen, osmotic pressure, and glutamate dehydrogenase (GDH) of L. vannamei juveniles acclimated during 18 days at a salinity of 15 per thousand and 40 per thousand. The second experiment was done to evaluate the effect of dietary CBH level on pre- and postprandial oxygen consumption, ammonia excretion, and the oxygen-nitrogen ratio (O/N) of juvenile L. vannamei in shrimps acclimated at 40 per thousand salinity. We also evaluated the ability of shrimp to carbohydrate adaptation. We made phosphoenolpyruvate carboxykinase (PECPK) and hexokinase activity measurements after a change in dietary carbohydrate levels at different times during 10 days. The growth rate depended on the combination salinity-dietary CBH-protein level. The maximum growth rate was obtained in shrimps maintained at 15 per thousand salinity and with a diet containing low CBH and high protein. The protein in hemolymph is related to the dietary protein levels; high dietary protein levels produced a high protein concentration in hemolymph. This suggests hemolymph is able to store proteins after a salinity acclimation. Depending on the salinity, the hemolymph proteins could be used as a source of osmotic effectors or as metabolic energy. The O/N values obtained show that shrimp used proteins as a source of energy, mainly when shrimps were fed with low CBH. The role played by postprandial nitrogen excretion (PPNE) in apparent heat increase (AHI) (PPNE/AHI ratio) is lower in shrimps fed diets containing high CBH in comparison with shrimps fed diets containing low CBH levels. These results confirm that the metabolism of L. vannamei juveniles is controlled by dietary protein levels, affecting the processes involved in the mechanical and biochemical transformations of ingested food. A growth depression effect was observed in shrimps fed with low-CBH protein diets and maintained in 40 per thousand salinity. In these shrimps, the hemolymph ammonia concentration (HAC) was significantly higher than that observed in shrimps fed with low CBH and maintained in 15 per thousand salinity. That high HAC level coincided with lower growth rate, which suggests that this level might be toxic for juveniles of L. vannamei. Results obtained for GDH activity showed this enzyme regulated both HAC and hemolymph protein levels, with high values in shrimps fed with low CBH levels and maintained in 40 per thousand salinity, and lower in shrimps fed with high CBH and maintained in 15 per thousand salinity. These differences mean that shrimp with a high-gill GDH activity might waste more energy in oxidation of the excess proteins and amino acids, reducing the energy for growth. It was evident that L. vannamei can convert protein to glycogen by a gluconeogenic pathway, which permitted shrimp to maintain a minimum circulating glucose of 0.34 mg/ml in hemolymph. A high PECPK activity was observed in shrimps fed a diet containing low CBH level indicating that the gluconeogenic pathway is activated, as in vertebrates by low dietary CBH levels. After a change in diet, we observed a change in PEPCK; however, it was lower and seems to depend on the way of adaptation, because it occurred after 6 days when adapting to a high-CBH diet and with little change for the low-CBH diet.     

Effects of low salinity media on growth, condition, and gill ion transporter expression in juvenile Gulf killifish, Fundulus grandis

The Gulf killifish, Fundulus grandis, is a euryhaline teleost which has important ecological roles in the brackish-water marshes of its native range as well as commercial value as live bait for saltwater anglers. Effects of osmoregulation on growth, survival, and body condition at 0.5, 5.0, 8.0 and 12.0‰ salinity were studied in F. grandis juveniles during a 12-week trial. Relative expression of genes encoding the ion transport proteins Na(+)/K(+)-ATPase (NKA), Na(+)/K(+)/2Cl(-) cotransporter(NKCC1), and cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel was analyzed. At 0.5‰, F. grandis showed depressed growth, body condition, and survival relative to higher salinities. NKA relative expression was elevated at 7 days post-transfer but decreased at later time points in fish held at 0.5‰ while other salinities produced no such increase. NKCC1, the isoform associated with expulsion of ions in saltwater, was downregulated from week 1 to week 3 at 0.5‰ while CFTR relative expression produced no significant results across time or salinity. Our results suggest that Gulf killifish have physiological difficulties with osmoregulation at a salinity of 0.5‰ and that this leads to reduced growth performance and survival while salinities in the 5.0-12.0‰ are adequate for normal function.     

Effects of salinity and temperature on oxygen consumption in a freshwater population of Palaemonetes antennarius (Crustacea,decapoda)

• 1.1. After step-like increases in salinity the shrimps exhibit the smallest increase in oxygen consumption in the lower salinity range. At higher salinities the shrimps show longer recovery times and greater increases in the metabolic rate after salinity shock.
• 2.2. In steady-state experiments, the shrimps display the lowest oxygen consumption rates near the isosmotic point. The lowest metabolic rates occur at salinities of 3‰ and 10‰ At salinities of 20‰ and above the rate of metabolism increases by 20–30%.
• 3.3. The calculated osmoregulatory work for animals in fresh water amounts to only 2.7% of routine metabolism and drops to 1.1% for shrimps in 3‰ and 0.7% in 5‰ salinity.
• 4.4. Locomotory activity in the form of position change was not responsible for the increased oxygen consumption of the animals after salinity shocks. A “tentative swimming activity” by fast and frequent beating of the pleopods without position change may be an important factor in the increase of metabolic rates.
• 5.5. In its temperature response, the brackish water population has a higher metabolic rate than the freshwater one. Between 5 and 35°C Q ₁₀-values range from 4.01 to 1.37.

     

Effect of chronic Taura syndrome virus infection on salinity tolerance of Litopenaeus vannamei

Taura syndrome virus (TSV) is one of the most important shrimp viruses affecting farmed shrimp worldwide. After an acute phase during which the likelihood of mortality is elevated, infected shrimp enter a chronic phase during which shrimp appear to resume normal behavior and display no gross signs of infection. This study was designed to determine if chronically TSV-infected shrimp Litopenaeus vannamei are compromised by the infection. Specifically we investigated whether chronically infected shrimp could tolerate a drop in salinity as strongly as uninfected shrimp. The study consisted of 3 trials that compared survival of uninfected and chronically TSV-infected L. vannamei after drops in salinity from 24 ppt to salinities varying from 18 to 0 ppt. Logistic regression detected a significant effect of TSV infection on survival of chronically infected shrimp (p < 0.05). Salinity drops from 24 ppt to 3 and 6 ppt resulted in statistically different survivals (p < 0.05). Survival rates were similar among groups for salinity drops to greater than 6 ppt or less than 3 ppt. Salinities at which 50% of the shrimp died (LC50) were 3.06 ppt for the uninfected and 6.65 ppt for the chronically infected groups. Moreover, histopathological analysis of chronically infected shrimp that were moribund or recently dead showed no signs of having reverted to the acute stage of the disease. These results suggest that chronically infected shrimp are not able to tolerate a salinity drop as strongly as uninfected shrimp.     

The effects of temperature and salinity on the swimming ability of whiteleg shrimp, Litopenaeus vannamei

Swimming endurance of whiteleg shrimp, Litopenaeus vannamei exposed to various temperatures (15, 20, and 25 degrees C) and salinities (15, 32, and 40 per thousand) was determined in a swimming channel against one of five flow velocities (5.41, 6.78, 8.21, 10.11, and 11.47 cm s(-1)) for up to 9000 s. No shrimp swam the full 9000 s throughout the experiment. The swimming endurance decreased as swimming speed was increased at any of the temperatures and salinities tested and was significantly affected by temperature and salinity (P<0.05). The power model (nu x t(b) = a) showed a better fit to the relationship between swimming endurance (t, in s) and swimming speed (nu, in cm s(-1)) at any of the temperatures and salinities tested. The swimming ability index (SAI), defined as SAI = integral(0)(9000) vdt x 10(-4) (cm), was found to be temperature- and salinity-dependent in L. vannamei. The optimum temperature and salinity and corresponding maximum SAI were Topt = 21.3 degrees C and SAI(max21.3) = 7.37 cm; Sopt = 27.6 per thousand and SAI(max27.6) = 7.47 cm, respectively. The range of temperatures and salinities within which SAI is >90% of the maximum was estimated between 17.6 and 24.9 degrees C and between 18.5 and 36.7 per thousand, respectively. The results suggest that the power model fits well to the observed endurance estimates and the SAI is a good index to quantitatively describe the overall swimming ability of L. vannamei. Furthermore, temperature and salinity can limit the swimming performance of L. vannamei.     

低蛋白质饲料中添加色氨酸对凡纳滨对虾饲料表观消化率、消化酶活和全虾氨基酸组成的影响

研究旨在探讨低蛋白质饲料中添加色氨酸对凡纳滨对虾饲料表观消化率、消化酶活以及全虾氨基酸组成的影响。试验选取初始体重为(2.000.01) g对虾960尾, 随机分成6组, 每组4个重复。各组分别投喂含40.79%粗蛋白质的高蛋白基础饲料(HT0)、含37.01%粗蛋白质的低蛋白基础饲料并添加0 (LT0)、1.20(LT1)、2.50 (LT2)、5.00 (LT3)和10.00 (LT4)g/kg色氨酸的6种饲料。饲养56d后采样、分析蛋白酶活和全虾氨基酸组成; 在此基础上投喂含0.04%三氧化二钇(Y2O3)的相应饲料进行消化率试验。结果表明:低蛋白质饲料中添加色氨酸可提高对虾蛋白质、氨基酸、干物质、能量的表观消化率, 蛋白酶活和影响全虾氨基酸组成(P0.05)。LT3、LT4粗蛋白质表观消化率显著高于LT0(P0.05)。LT3蛋氨酸表观消化率显著高于LT0, LT3酪氨酸表观消化率显著高于HT0 (P0.05)。LT3和LT4干物质表观消化率显著高于LT0 (P0.05)。LT1、LT2、LT3和LT4总能表观消化率均高于LT0, 但仅LT4达显著水平(P0.05)。LT2肠蛋白酶活最高, 并显著高于HT0和LT1 (P0.05), LT2、LT3、LT4肝胰腺蛋白酶活显著高于LT0 (P0.05), 但与HT0相比无明显差异(P0.05)。LT4全虾天门冬氨酸、甘氨酸、丙氨酸、蛋氨酸、亮氨酸含量均明显高于LT0 (P0.05)。LT1全虾赖氨酸含量显著高于LT0 (P0.05)。由此可见, 低蛋白质饲料中添加色氨酸可明显提高凡纳滨对虾饲料蛋白质、氨基酸、干物质和能量的表观消化率、蛋白酶活, 并改善全虾氨基酸的组成。