Effects of low salinity exposure on immunological,physiological and growth performance in Litopenaeus vannamei

Growth, immunological and physiological parameters of white shrimp Litopenaeus vannamei reared at different salinity levels (1, 10, 15, 25 and 35 g/L) at stocking density of 214 shrimp/m³ were examined at 1, 30 and 63 days. Results showed that the total haemocyte count (THC) of shrimp decreased with time at all salinity levels, indicating a potential reduction in the resistance of shrimp against pathogens, since a low value of THC indicates a perturbation of the immune system. Glucose and protein values observed in the haemolymph throughout the study indicate that shrimp adapted well to low salinities (1, 10 and 15 g/L). Although of those shrimp reared at 10 g/L only 83.3% survived, at this salinity, shrimp depicted a higher glucose concentration in haemolymph at the beginning and end of the study.     

禁食状态下凡纳滨对虾游离氨基酸的降解代谢

在禁食胁迫下,对在盐度为0(S0)和30(S30)水体中的凡纳滨对虾肌肉游离氨基酸(FAA)的浓度变化进行测定.结果表明,禁食15d后,两种盐度中的凡纳滨对虾肌肉游离氨基酸总量均有所升高,但其中游离的牛磺酸(Tau)、苏氨酸(Thr)、脯氨酸(Pro)、丙氨酸(Ala)、半胱氨酸(Cys)、缬氨酸(Val)、蛋氨酸(Met)、异亮氨酸(Ile)、亮氨酸(Leu)、苯丙氨酸(Phe)、赖氨酸(Lys)、组氨酸(His)的浓度却有不同程度的降低,脯氨酸(Pro)在禁食15d后的浓度降为0,牛磺酸(Tau)、苏氨酸(Thr)、丙氨酸(Ala)、半胱氨酸(Cys)、苯丙氨酸(Phe)、赖氨酸(Lys)的降幅也比较显著(P<0.05);但甘氨酸(Gly)、天门冬氨酸(Asp)、酪氨酸(Tyr)、精氨酸(Arg)等主要游离氨基酸的浓度却显著升高,从而使游离氨基酸总浓度升高.实验表明,凡纳滨对虾肌肉里游离氨基酸浓度在禁食胁迫下降解代谢强度不一,饲料中添加脯氨酸(Pro)、精氨酸(Arg)和赖氨酸(Lys)等游离氨基酸后,可能会对凡纳滨对虾的生长起到促进作用.     

Dietary lipid requirement of whiteleg shrimp Litopenaeus vannamei juveniles cultured in biofloc system

An eight‐week feeding trial was conducted to evaluate the contribution of biofloc on dietary lipid requirement in whiteleg shrimp Litopenaeus vannamei. Five diets with graded levels of dietary lipid (45, 60, 90, 120 and 150 g/kg) were fed to juvenile shrimp. Final weight, weight gain and specific growth rate of shrimp fed diets with 60, 90 and 120 g/kg lipid levels were significantly higher than those of shrimp fed diets with lipid levels 45 and 150 g/kg (p < .05). Feed efficiency and protein efficiency ratio of shrimp fed 60, 90 and 120 g/kg were higher than those fed 150 g/kg diet. Plasma total cholesterol and triglyceride levels were lower in shrimp fed 45 g/kg compared with those fed the 90 g/kg (p < .05). Also, lysozyme activity for 90 g/kg group was higher than the 15 g/kg group. Hepatopancreas lipase and amylase activities of shrimp fed 90 and 120 g/kg diets were significantly higher than those of shrimp fed 45 and 150 g/kg diets. Broken‐line regression analysis for weight gain indicated that the dietary lipid requirement of whiteleg shrimp juveniles reared in a biofloc system was estimated to be higher than 56 g/kg but <60 g/kg.     

凡纳滨对虾的游泳能力及游泳疲劳后的生理反应

在水温(24.8±0.3)℃条件下,测定了凡纳滨对虾(Litopenaeus vannamei)的l临界游速(Ucrit)、弹跳速度、不同流速下的可持续游泳时间,以及游泳疲劳后的生理反应.实验凡纳滨对虾体长(6.87±0.42)cm,体质量(3.34±0.59)g;5个水流速度分别设定为(26.7±2.9)cm·s-1、(31.0±3.6)cm·s-1、(34.6±3.7)cm·s-1、(38.6±3.3)cm·s-1、(4018±3.4)cm·s-1.结果表明,凡纳滨对虾游泳足的摆动频率与流速呈线性甬数关系,可持续游泳时间与流速呈对数函数关系.其游泳能力指数SAI(Swimming.Ability Index)为16.49cm,平均临界游速为(35.67±0.62)cm·s-1[(5.02±0.09)BL·s-1],平均弹跳速度为(106.51±6.08)cm·s-1[(15.74±0.96)BL·s-1].不同流速下游泳疲劳后,凡纳滨对虾血糖和血浆乳酸浓度均显著高于对照组(P＜0.05);在26.7 cm·s-1、31.0 cm·s-1和34.6 cm·s-1流速下游泳疲劳后,血浆甘油三酯浓度均极显著高于对照组(P＜0.01、);在26.7 cm·s-1、34.6 cm·s-1和38.6 cm·s-1流速下游泳疲劳后,血浆总蛋白浓度均显著高于对照组(P＜0.05).经临界游速和弹跳速度测试疲劳后,血糖和血浆乳酸浓度也均显著升高(P＜0.05),而血浆甘油三酯和总蛋白浓度则无显著变化(P＞0.05).本研究旨在深入了解对虾运动生理学特性,并为对虾捕捞和增养殖技术的改良提供参考依据.     

饥饿对凡纳滨对虾仔虾摄食行为和消化酶活力的影响

2004年5月,在中国海洋大学海水养殖教育部重点实验室内营造半精养、精养养殖模式,研究短期饥饿(0(对照组)、1、2、3、4、5、6d)对凡纳滨对虾仔虾摄食行为、摄食率及消化酶的影响。结果表明,两种模式中仔虾的摄食行为和摄食率都随饥饿天数的增加而呈现先上升后下降的趋势;半精养模式中,经饥饿再投喂后仔虾的胃蛋白酶、类胰蛋白酶和淀粉酶活力均随饥饿天数的增加呈现先上升后下降的趋势;精养模式中,胃蛋白酶活力也呈现以上趋势,但类胰蛋白酶和淀粉酶活力则在饥饿初期波动,然后下降。凡纳滨对虾仔虾遭遇饥饿胁迫后,通过提高摄食强度、摄食率及消化酶的分泌量来进行能量补充。但随着饥饿时间的延长,其应对饥饿胁迫的能力下降,各种消化酶活力呈降低趋势。实验表明,在半精养模式中,凡纳滨对虾对饥饿胁迫的承受能力高于精养模式。     

壳寡糖对南美白对虾生长和血清生化指标的影响

为研究壳寡糖对南美白对虾(初始体重约1.23 g)的生长和血清生化指标影响,设置了含壳寡糖0 mg/kg、125 mg/kg、250 mg/kg、500 mg/kg、1000 mg/kg的5组试验饲料,经过8周的饲养实验。结果表明,不同含量的壳寡糖对南美白对虾的增重率、特定生长率、饲料系数和成活率均无显著影响(P>0.05);对南美白对虾血清中的肌酐、葡萄糖、钙离子、总胆固醇、甘油三脂和低密度脂蛋白胆固醇均无显著影响,但可使高密度脂蛋白胆固醇显著增加,促进脂类代谢;综合试验结果得出饲料中壳寡糖添加250~500 mg/kg为宜。     

凡纳滨对虾蛋白酶的分离纯化及生化特性

采用Tris-HCl缓冲液抽提、Sephadex G-100凝胶过滤层析、DEAE-Sepharose F.F.阴离子交换层析和SDS-PAGE等方法,分离和纯化了凡纳滨对虾蛋白酶,研究了其生化特性.试验结果表明,该蛋白酶粗提物经层析后,得到聚丙烯酰胺凝胶电泳纯的一酶组分.该蛋白酶的比活力从128.35 U/mg增至1835.65 U/mg,提高了14.3倍,产率达31.9%.SDS-PAGE显示该蛋白酶只含一条谱带,相对分子量为25 kD.以酪蛋白为底物,该酶的最适pH为7.0,最适温度为60 ℃, 在50 ℃以下,比较稳定,放置1 h后活性仍超过60%,而超过50 ℃时蛋白酶活性急剧下降,60 ℃放置1 h后,酶活性只残留4.7%.10 mmol/L EDTA、Fe~(2+)、Ba~(2+)和Zn~(2+)对该蛋白酶有较强的抑制作用,抑制率分别为84%、53%、43%和38%,10 mmol/L Mg~(2+)和Cu~(2+)对蛋白酶活性有轻微抑制作用,而10 mmol/L Ca2+能显著促进蛋白酶活性,据此推测凡纳滨对虾蛋白酶可能为一种金属蛋白酶.     

Dopamine induces transient modulation of the physiological responses of whiteleg shrimp,Litopenaeus vannamei

Levels of glucose, lactate, Na⁺, K⁺, Cl⁻, protein, and oxyhemocyanin in the hemolymph and its osmolality were measured when the whiteleg shrimp (Litopenaeus vanammei; 20 ± 1.5 g), were individually injected with saline or dopamine at 10^− 8, 10^− 7, or 10^− 6 mol shrimp^− 1. Results showed that elevations of hemolymph glucose and lactate occurred at between 2 and 4 h, increases in hemolymph osmolality, Cl⁻, Na⁺, and total protein occurred at 2 h, and a reduction in hemolymph oxyhemocyanin occurred at 4 h after the dopamine injection. All physiological parameters except K⁺ had returned to the control values 8–16 h after receiving the dopamine. The injection of dopamine also significantly decreased the oxyhemocyanin/protein ratio of L. vannamei at 2 h as a result of the elevation of hemolymph protein. These results suggest that stress-inducing dopamine causes a transient period of modulation of energy metabolism, osmoregulation, and a respiratory response in L. vannamei in adapting to an environmental stress.     

Effect of plant protein concentrates on nutrition physiology of Litopenaeus vannamei (Boone, 1883) juveniles

This study was designed to test the effect of soy protein (SPC), wheat gluten (WHG) and potato protein (PPC), in vitro and in vivo digestibility of protein and energy in the juveniles Litopeneaus vannamei. A completely random design was used with nine 400‐L tanks (with three repetitions by treatment). Ten respirometric chambers (500 mL) were used for energy distribution. In vitro digestibility for SPC (8.8%) was higher than for PPC (5.8%) and for WHG (4.3%, P < 0.05). Diets’ degree of hydrolysis ranged between 0.75% and 1.2%, with lowest value in potato protein concentrate diet (0.75 ± 0.09%, P < 0.05). No significant differences were obtained in apparent digestibility coefficient (ADC) for protein (63.4–74.1%). ADC for amino acids ranged between 80% and 90%. Daily growth coefficient ranged from 0.86% to 1.1% day⁻¹, being the best in soybean protein concentrate diet (SPCd) (P < 0.05). Significant differences on heat increment were observed (P < 0.05); highest value was in wheat gluten diet (1.0 ± 0.1 kJ shrimp day⁻¹) that coincided with a peak of trypsin specific activity (16.5 ± 3.7 mU mg protein⁻¹). Highest retained energy for growth was observed in shrimp fed SPCd (0.7 ± 0.03 kJ day⁻¹, P < 0.05). Muscle collagen content presented a minimum of bands with SPCd, whereas shrimp post‐mortem collagenase activity was not affected by any of the three diets (P > 0.05).     

贮藏过程中凡纳滨对虾生物胺的变化

以邻苯二甲醛(OPA)为柱后衍生化试剂,采用反相HPLC法测定凡纳滨对虾(Litopenaeus vannamei)中的酪胺(Tyr)、腐胺(Put)、尸胺(Cad)、组胺(His)、胍丁胺(Agm)、精胺(Spe)和亚精胺(Spd)等7种生物胺。结合虾的感官分析、pH值和T-VBN值测定等方法评价凡纳滨对虾的品质,分析了凡纳滨对虾在不同贮藏温度和贮藏时间下的生物胺种类及含量的变化。结果表明,在0和4℃两种贮藏温度下,尸胺和腐胺发生的变化均最显著,可以其作为凡纳滨对虾新鲜程度的参考指标,确定最长贮藏时间分别为8d和6d。     

凡纳滨对虾幼虾低盐度粗养水体养殖容量的研究

试验设计6个凡纳滨对虾幼虾养殖密度:10、20、30、40、50、60 ind/m2,通过比较60 d养殖周期内的水环境因子、幼虾生长状况与消化酶活性,分析研究凡纳滨对虾幼虾低盐度粗养水体的养殖容量。结果表明:各试验组水质均符合凡纳滨对虾幼虾生长要求,单位水体载虾量主要影响pH、非离子氨氮(NH3-Nm)、溶解氧(DO)等水化指标;不同试验组水体pH、NH3-Nm含量、DO含量、总氮(TN)含量差异极显著(P0.01),浊度、总磷(TP)含量差异显著(P0.05);不同试验组对虾中肠腺蛋白酶活性差异显著(P0.05),表现出单位水体载虾量越高,对虾体内蛋白消化酶活性和氮利用率越低的规律,DO是低盐度粗养水体养殖容量的主要限制因子。综合各项评价指标,得到本试验条件下,凡纳滨对虾幼虾低盐度粗养水体的最佳养殖容量为46.0 g/m3或32.2 g/m2(322 kg/hm2)。     

Effects of different levels of dietary protein on the growth performance,nutrient utilization,digestive enzymes and physiological status of white shrimp,Litopenaeus vannamei juveniles reared in inland saline water

A 60‐day feeding trial was conducted to illustrate the effect of dietary protein levels on the growth and physio‐metabolic responses of juvenile Litopenaeus vannamei reared in inland saline water (ISW). Six isoenergetic (15 MJ/kg) and isolipidic (60 g/kg) diets with graded level of crude protein viz., 240 (T240), 260 (T260), 280 (T280), 300 (T300), 320 (T320) and 340 (T340) g/kg diet were formulated. Significantly higher (p < .05) weight gain (%), specific growth rate, with lower food conversion ratio were found in T320 and T340 groups. The protein utilizing efficiency and whole‐body protein content were significantly higher (p < .05) in the T320 group. Trypsin activity increased with the increasing dietary CP level but amylase activity decreased with the increasing dietary CP level. Transaminase enzymes, haemolymph protein and haemocyanin were elevated in T320 and T340 groups. The lactate dehydrogenase and malate dehydrogenase activities were significantly higher (p < .05) in the T240 group. Shrimp of T240 group had the lowest (p < .05) glycogen and total haemocyte count with highest (p < .05) haemolymph glucose and antioxidant enzymes activities than the other groups. Based on the results, feeding 320 g CP/kg is found to be optimum for supporting maximum growth and health status of L. vannamei reared in ISW at 8 g/L salinity. The finding of the present study will help in developing a low‐cost feed for L. vannamei reared in ISW.     

Changes in Biochemical Compositions and Quality of White Shrimp (Litopenaeus vannamei) During Storage

ABSTRACT

To understand biochemical characteristics, storage stability, and freshness indicators of white shrimp (Litopenaeus vannamei), changes in extractable nitrogenous compounds, microbial count, and sensory rating of white shrimp during storage at 25 and 4°C were investigated. Free amino acids showed a slow increase during storage at 25°C, but no obvious change was found at 4°C. Adenosine triphosphate (ATP) and adenosine diphosphate (ADP) were found at initial stage and decreased rapidly after storage. Both inosine 5′-monophosphate (IMP) and adenosine monophosphate (AMP) increased and then decreased during storage. Inosine, hypoxanthine, and the K-value gradually increased with time. The levels of total volatile basic nitrogen (TVB-N), NH₃, and trimethylamine (TMA) of white shrimp increased with storage time at 25 and 4°C. The TVB-N, NH₃, TMA, inosine, hypoxanthine, and K-value could be considered as freshness indicators of white shrimp during storage. However, the total plate count did not corroborate the acceptability recommended limits for white shrimp during storage. The sensory evaluation, associated with TVB-N, TMA, and K-value, showed the quality was unacceptable after 6 h storage at 25°C and 7 days at 4°C.     

微生态净水剂对凡纳滨对虾生理生化指标的影响

为了证实微生态净水剂(含菌量10×109/g)可以提高虾体免疫力和对污染物(如农药)的抵抗力,在凡纳滨对虾(Litopenaeus vannmei)养殖过程中,设置了施用微生态净水剂的实验组和未用微生态净水剂的对照组,采用肌肉注射的方式,对2组凡纳滨对虾进行乙酰甲胺磷毒性实验。注射乙酰甲胺磷后,采样测定血细胞吞噬化学发光情况,组织中超氧化物歧化酶(SOD)、过氧化物酶(POD)、溶菌酶(LSZ)、酯酶活性以及酯酶(EST)、苹果酸脱氢酶(MDH)同工酶表型变化。结果表明:施用微生态净水剂组明显好于对照组。施用微生态净水剂的虾注射乙酰甲胺磷后死亡率降低,血细胞的吞噬功能也有所增加,虾体组织内SOD、POD、LSZ、酯酶活性变化较未用组的虾变化幅度较小,其中,SOD、POD活性等高于未用组,EST、MDH同工酶酶带数目也有增加。说明微生态净水剂从本质上增强虾体内代谢、提高虾体的免疫力、增强其对外界环境变化适应能力,并具有提高虾体防御功能,增强抵抗疾病能力的作用。     

南美白对虾与河蟹的池塘混养试验

面积均为0．4hm^2的试验池塘4口，每口池塘放养蟹苗8500只、南美自对虾苗5万～15万尾、鲢鳙老口苗60尾；饲养120d，总产值150547元，总利润80719元。投入产出比为l：2．2；虾蟹池塘混养。蟹种放养规格以160只／kg、虾苗以5万～lO万尾／hm^2较为适宜。     

Dietary magnesium requirement and physiological responses of marine shrimp Litopenaeus vannamei reared in low salinity water

An 8‐week feeding experiment was conducted to determine the dietary magnesium (Mg) requirement and physiological responses of Litopenaeus vannamei in low salinity water of 2 g L^?1. Casein–gelatin‐based diets supplemented with seven levels of Mg (0, 0.4, 0.8, 1.6, 3.2, 6.4 and 8.0 g kg^?1) were fed to juvenile shrimp. Prior to the experiment, the postlarvae were gradually acclimated to the low salinity media and fed with a basal diet (0.5 g Mg kg^?1) for 2 weeks. After 8 weeks of feeding, survival ranged from 80.11% to 85.65% with no significant difference among the treatments. Hepatopancreas Mg²⁺‐ATPase and Na⁺/K⁺‐ATPase activities and muscle content of lipid and protein were not significantly affected by graded levels of Mg. The weight gain and mineral (calcium, potassium, sodium and total phosphorus) content of different tissues were significantly affected by dietary Mg levels, while there were no significant differences in ash and zinc content in tissues. The Mg content in tissues except hepatopancreas was maintained relatively constant regardless of dietary treatments. The dietary Mg requirement for optimal growth was 2.60–3.46 g Mg kg^?1 by using the polynomial regression analysis based on growth.     

Daily activity pattern of the marine shrimp Litopenaeus vannamei (Boone 1931) juveniles under laboratory conditions

Lack of information on the daily activity patterns of Litopenaeus vannamei (Boone 1931) might result in inadequate feed management strategies in shrimp farms. In order to provide information to improve feed management in shrimp farms, the daily activity of juvenile shrimp reared in glass aquaria was studied, using L. vannamei (7.57±1.01 g), equivalent to 33 shrimp m^?2. Thirty‐two shrimp were observed, half in light and half in dark phase, over 280 h in 15 min h^?1 windows. Feed was provided once a day, at 10% of tank biomass. Swimming, exploration of substrate, inactivity and cleaning were recorded through instantaneous focal sampling. During the dark phase, swimming was predominant and alternated with exploration. In the light phase, inactivity was predominant, and again alternated with exploration. Cleaning occurred evenly in both the light and the dark. Substrate exploration, which characterizes the search for food, occurred in both dark and light phases, with a most intense peak 7 h after light phase onset, indicating this as the optimal feed offer.     

浓海水条件下凡纳滨对虾血清免疫生理指标比较

为探索利用海水淡化产生的浓海水开展水产养殖的可能性,研究了凡纳滨对虾对浓海水的应激免疫反应.实验用浓海水由盐度30的天然海水添加粗盐配制而成.实验组设盐度40和36两种,对照组为自然海水盐度30.分别检测凡纳滨对虾高盐度应激后0、2、6、12、24、48、96 h时的血清蛋白含量和酸性磷酸酶、超氧化物歧化酶、血清溶菌酶活性、血清凝血时间.结果表明,浓海水对凡纳滨对虾血清蛋白含量、酸性磷酸酶活性和血清凝血时间均有极显著影响（P＜0.01）,但对凡纳滨对虾血清溶菌酶活性、超氧化物歧化酶活性无显著影响（P＞0.05）.     

凡纳滨对虾亲虾繁殖期间适宜投喂频率的研究

在饱食投喂条件下,选用鲜活饵料沙蚕(Nereis succinea)对凡纳滨对虾(Litopenaeus vannamei)亲虾进行营养强化培育60 d,通过比较不同的投喂频率2次/d(F2组)、3次/d(F3组)、4次/d(F4组)对亲虾摄食、生长、繁殖性能、虾体组成和肝胰腺的消化酶活力的影响,旨在探究亲虾繁殖期间营养强化的最适投喂频率。结果显示,随着投喂频率的增加,亲虾的日摄食量逐渐增大,F2组显著低于F4组(P0.05),但与F3组差异不显著(P0.05);亲虾的增重率和体长增长率呈先升高后降低的趋势,但无显著性差异(P0.05)。不同的投喂频率对各组亲虾的单次产卵量、相对产卵量、无节幼体I期个体数、无节幼体孵化率、蚤状幼体I期个体数、无节幼体变态率、性腺指数、初产时间和产卵间期均无显著影响(P0.05)。亲虾全虾主要体组成分水分、粗蛋白、粗脂肪、灰分含量也不受投喂频率增加的影响(P0.05);F2组的胰蛋白酶和脂肪酶活力显著低于F3、F4组(P0.05),而不同实验组的胃蛋白酶和淀粉酶活力无显著性差异(P0.05)。结合本研究的结果和生产实际情况,建议在饱食投喂条件下,凡纳滨对虾亲虾繁殖期间营养强化的适宜投喂频率为2次/d。     

Changes in the intestinal bacterial community during the growth of white shrimp,Litopenaeus vannamei

In this study, we documented the changes in the intestinal bacterial community at four stages in Litopenaeus vannamei: 14 days postlarvae (L14) and 1‐, 2‐ and 3‐month old juveniles (J1, J2, J3), using 454 pyrosequencing techniques. The intestinal bacterial community was dominated by three bacterial phyla, Proteobacteria, Bacteroidetes and Actinobacteria at all stages. However, the relative abundance and bacterial lineages varied at the family level. The intestinal bacterial community of L14 and J1 was similar, with dominant members belonging to the Comamonadaceae of Betaproteobacteria. Conversely, bacterial members affiliated to Flavobacteriaceae of Bacteroidetes were dominant in J2 and Vibrionaceae of Gammaproteobacteria was dominant in J3. The abundance of Microbacteriaceae of Actinobacteria also fluctuated during the four stages. Bacterial members of Flavobacteriaceae and Rhodobacteraceae (Alphaproteobacteria) were present through all growth stages, and likely form the intestinal core microbiome of L. vannamei. However, they varied at the operational taxonomic unit (OTU) level through the growth stages. The intestinal bacterial community of pond‐rearing shrimp included the three main bacterial phyla identified above, and an additional group, Mycoplasmataceae of Mollicutes. Our results demonstrate that the intestinal bacterial community of L. vannamei was highly dynamic during the growth stages. Bacterial members belonging to Commamonadaceae dominated in the earlier growth stage of shrimp, possibly influenced by feeding with Artemia nauplii, but there was a shift to Flavobacteriaceae in the mid and Vibrionaceae in the late growth stages.