Larviculture of the painted river prawn Macrobrachium carcinus in different culture systems

The objective of this study was to evaluate different hatchery systems used for the larviculture of the Macrobrachium carcinus based on survival, larval development and production of post-larvae. The experimental culture was carried out in three phases designated as Phase I (Zoea VI to VIII – Z_{VI – VIII}), Phase II (Zoea VIII to X – Z_{VIII – X}), and Phase III (Zoea X to PL – Z_{X – PL}), with densities of 30, 27.5 and 25 larvae / L, respectively. The M. carcinus larvae (Z_VI) were reared in four culture systems, two being open (Greenwater – GW and Clearwater – CW) and two being closed (Biofloc – BFT and Bio-filter – RAS), distributed in twelve 10 L plastic containers, filled with 20 ppt brackish water, equipped with constant aeration, and water circulated by air lift and heated with thermostat (∼30 °C). The GW treatment was maintained with Chlorophyceae algae in the density of 3–5 × 10⁵ cells/mL. In the CW, the water was previously filtered through a 5 μm mesh screen, sterilized with 10 ppm active chlorine and, dechlorinated with vitamin C and subjected to aeration for 24 h. The BFT received water rich in bioflocs that was matured prior to the experiment and used molasses as a source of organic carbon. In the RAS, the culture water circulated through an external “Dry-Wet” biological filter. The feeding was carried out ad libitum four times daily, alternating a wet diet formula with a commercial diet, which was supplemented with newly hatched Artemia nauplii at a rate of 40–50 per larvae/day. Temperature, dissolved oxygen and pH were monitored daily and the salinity two times per week. Total ammonia, nitrite, nitrate, orthophosphate, alkalinity, total suspended solids, chlorophyll-a, COD and BOD were also analyzed. The best water quality (P < 0.05) was obtained in the RAS, with 0.49 (±0.38), 0.23 (±0.22), and 9.0 (±1.5) mg/L of TAN, NO₂-N and NO₃-N, respectively. In the GW, the nitrogen species showed high fluctuations and higher concentrations at 2.32 (±1.68), 3.53 (±3.53) and 18.2 (±12.9) mg / L of TAN, NO₂-N and NO₃-N, respectively. Considering the three phases (Z_{VI – PL}), the overall survival was 0.03, 1.97, 2.23 and 17.32 % for the BFT, CW, GW and RAS, respectively. When considering the phases separately, the survival in Phase I (Z_{VI – VIII}) was highest in the GW system at 58.7 % while the RAS was the highest in Phases II (Z_{VIII – X}) and III (Z_{X – PL}) at 70.6 % and 60.3 %, respectively. The BFT showed 8.4 (±3.5) PL/L, which was higher (P < 0.05) than that obtained in the RAS (2.8 ± 1.2 PL/L) and the GW (1.3 ± 1.1 PL/L) and similar to that obtained in the CW (5.6 ± 2.0 PL/L). Thus, the larviculture for the M. carcinus may be optimized by adopting a multiphase management strategy, which the intermediate larval stages (Z_{VI – IX}) are reared in the GW system and the final stages (Z_{X – PL}) are reared in the BFT system.     

南美白对虾淡水养殖试验报告

采取人工调兑淡水盐度，定点投喂颗粒饲料，调节水质及病害预防措施，在667m^2淡水池塘中养殖南美白对虾，经107天的饲养管理，共产南美白对虾160．2kg，平均体长达13．5cm/尾，体重20g/尾，成活率达到80．1％，共获利润5732．5元，投入产出比1：2．47。     

Expression of a recombinant crustacean hyperglycemic hormone of the kuruma prawn Penaeus japonicus in methylotrophic yeast Pichia pastoris

ABSTRACT:   Until now, six crustacean hyperglycemic hormones (CHH) designated Pej-SGP-I, -II, -III, -V, -VI and -VII have been characterized in the kuruma prawn Penaeus japonicus . All CHH consist of 72 amino acid residues and have an amidated carboxyl (C)-terminus. In the present study, we expressed Pej-SGP-III in methylotrophic yeast Pichia pastoris in order to obtain a large quantity of recombinant CHH possessing biological activity. A cDNA encoding Pej-SGP-III that had been previously cloned was processed by polymerase chain reaction (PCR) and the resulting product was ligated into an expression vector. Pichia pastoris was transformed with this vector after which a recombinant Pej-SGP-III was expressed having an additional amino acid residue (glycine) at the C-terminus (rPej-SGP-III-Gly), a form considered to be a putative precursor of this hormone. rPej-SGP-III-Gly secreted into the culture medium was purified by reversed-phase HPLC, and amidated using a peptidylglycine alpha-amidating enzyme. The amidated rPej-SGP-III (rPej-SGP-III) showed hyperglycemic activity in in vivo bioassay almost comparable to that of the natural Pej-SGP-III. rPej-SGP-III thus obtained will be a useful tool not only for its physiological study but also for the determination of its 3-D structure.     

中国对虾育苗时间与温度的关系及其应用

根据多年的调研和试验资料，利用非线性积温模型，模拟了对虾幼体各发育阶段所需天数与水温的关系。在此基础上研究确定了亲虾产卵孵化期的气候决策模式；并应用模式计算出了我市亲虾产卵孵化的适宜时段。为亲虾适宜产卵孵化期的决策提供了科学方法。     

松嫩平原碱水水域对虾体重生长速度与Ca~(2+)、Mg~(2+)的关系

以盐碱化湖泊和池塘水进行凡纳滨对虾(Litopenaeus vannamei Boone,1931)幼虾生长试验,探讨碱水环境对虾体重生长速度与Ca2 、Mg2 、Ca2 Mg2 质量浓度及(1/2Ca2 )/(1/2 Mg2 )的关系,为碱水水域养殖提供科学依据.结果表明,在碱度为10.32～38.50 mmol/L、盐度1.02～3.34g/L、pH 8.5～9.5的水环境中,体长为10～20 mm的幼虾饲养27 d的体重生长速度为(0.95 0.18)mg/d,存活率(47.5±14.5)%.不同水环境存活率差异显著(P＜0.01),体重生长速度差别不明显(P＞0.05).体重生长速度与环境因子问的相关性不明显.通过驯化提高幼虾对水环境的综合适应能力,是碱水水域养殖对虾的重要途径.     

Chemical and Thermal Properties of Freshwater Prawn (Macrobrachium rosenbergii) Meat

Chemical compositions and thermal properties of cultured freshwater prawn meat (FPM) were studied. FPM contained 83.2% protein (dry basis), 62.7% of which was myofibrillar protein. Pepsin-soluble collagen (PSC) and insoluble collagen (ISC) contents were 0.63 and 0.32%, respectively. Both collagens were similar to type V collagen from porcine placenta. Glutamic acid/glutamine, arginine, aspartic acid/?asparagine, and lysine were abundant amino acids in FPM. Glycine, proline, hydroxyproline, and aspartic acid/?asparagine were predominant in both collagens. FPM exhibited thermal transition temperatures (T_max) of 48.3 and 64.7°C, whereas T_max of PSC and ISC were 43.0 and 46.0°C, respectively. Textural changes in FPM during post-mortem storage on ice are plausibly dependent upon its compositional and thermal properties.     

Pathogenicity of halophilic Vibrio harveyi in giant freshwater prawns (Macrobrachium rosenbergii De Man)

In this study, the phenotypic and pathogenic properties in freshwater host were characterized in 14 strains of halophilic Vibrio harveyi isolated from infected marine black tiger shrimp, Penaeus monodon. The lysogenic phenotype was assayed via prophage excision and mitomycin C induction. The bacteria were grouped into two types, corresponding to lysogenic and non‐lysogenic strains. The pathogenicity was determined via direct injection of bacterial cultures into post‐larval juvenile giant freshwater prawns, Macrobrachium rosenbergii De Man. All of the infected prawns showed similar symptoms and inflamed hepatopancreas. The V. harveyi isolates derived from the first‐injected infected prawns were re‐isolated and re‐injected into healthy giant freshwater prawns, in which they retained similar infectivity. Both lysogenic and non‐lysogenic Vibrio spp. showed identical virulence associated with 100% mortality within one day post‐injection. TEM micrographs showed hepatopancreatic nuclear deformation and lipid breakdown caused by lysogenic γ‐hemolytic VL19 and non‐lysogenic β‐hemolytic V33. However, the V33 strain was associated with severely disrupted mitochondria. None of the V. harveyi strains was able to produce a biofilm. Together, our findings indicate that the lysogenic and non‐lysogenic halophilic V. harveyi isolated from marine shrimps may use different virulence factors that are responsible for their pathogenicity in freshwater prawns.     

The On-Farm Trials of the Rotational Prawn-Rice Farming in a Semi-Deep Water Area

ABSTRACT

The on-farm trials of rotational rice-prawn farming in a semi-deep water area in the Mekong Delta of Vietnam was carried out in six rice fields (0.7–1.0 ha) to evaluate the production and economic efficiency of using low and high cost feed on prawn culture in paddies at different densities. Two stocking densities of 4 and 5 PL/m² were investigated. Two treatments of feed types (pellets only or a combination of pellets, trash fish, and snail meat) were applied at stocking 4 PL/m². At the treatment of 5 PL/m², prawns were fed a combination of pellets, trash fish, and snail meat. Prawns were stocked in the mid-April and harvested in mid‐November before the next dry season rice crop. Rice farming was started 3 to 5 days after prawn harvesting. By cull harvesting during the culture period, final mean weights of prawn ranged from 47.2 to 57.2 g/prawn and the male:female ratio at harvesting was 2.5:1.0. The prawn yield of treatment 5 PL/m² was highest (630 ± 22 kg/ha). Net profits in treatments using the combination of pellets, trash fish, and snail meat were 861 ± 193 US$/ha to 1,019 ± 25 US$/ha for the prawn crop and 1,393 ± 71 US$/ha to 1,576 ± 180 US$/ha for the whole system (prawn crop + dry rice crop) and significantly higher than in treatment using pellet only (P < 0.05). Prawns fed on pellets or a combination of pellets and snail meat both offer similar results in terms of production and economics. The dry rice crop offered high cost benefit ratio (2.29–2.33) with low operating cost (414–434 USD/ha) and it made a better use in sustainable rice fields through the rotational rice-prawn system.     

日本对虾越冬亲虾性腺促熟及工厂化育苗技术研究

1997、1998年利用越冬亲虾进行性腺促熟,用镊烫法切除眼柄,促进亲虾发育。结果:两年共培育亲虾雌虾8204尾。雄虾5683尾,获交尾虾5360尾。交尾率为71.81％。每年两批育苗,共利用水体1720m~3,育出0.7～1.1cm的虾苗12450万尾,平均单位水体出苗量为7.24万尾/m~3,效益显著。     

C/N ratio control and substrate addition for periphyton development jointly enhance freshwater prawn Macrobrachium rosenbergii production in ponds

The present research investigated the effect of carbon/nitrogen ratio (C/N ratio) control in ponds with or without substrate addition for periphyton development on production of giant freshwater prawn. C/N ratios of 10, 15 and 20 were investigated in 40 m^− 2 ponds stocked with 2 prawn juveniles (5.023 ± 0.02 g) m^− 2 with or without added substrates for periphyton development. The various treatment combinations of C/N ratio and periphyton substrate addition are abbreviated as ‘CN10’, ‘CN15’, ‘CN20’, ‘CN10 + P’, ‘CN15 + P’ and ‘CN20 + P’, P representing periphyton substrate. A locally formulated and prepared feed containing 30% crude protein with C/N ratio10 was applied. Tapioca starch was used as carbohydrate source for manipulating C/N ratio and applied to the water column separately from the feed. Increasing the C/N ratio from 10 to 20 reduced (P < 0.001) the total ammonia-nitrogen (TAN), nitrite–nitrogen (NO₂–N) and nitrate–nitrogen (NO₃–N) in water column and total Kjeldahl nitrogen (TKN) in sediment. The addition of substrates only influenced the NO₂–N concentration in the water column (P < 0.001). Increasing the C/N ratio raised the total heterotrophic bacterial (THB) population in the water column, sediment and periphyton (P < 0.001). It also increased the dry matter (DM), ash free dry matter (AFDM), and chlorophyll a content of periphyton (P < 0.001). The lowest specific growth rate (SGR), the highest food conversion ratio (FCR), and the lowest protein efficiency ratio (PER) were recorded in treatment CN10 (P < 0.05). The addition of substrates did not influence size at harvest (P > 0.05) but improved the survival from 62.8 to 72% (P < 0.001). Increasing the C/N ratio from 10 to 20 increased the net yield by 40% and addition of substrate increased the net yield by 23%. The combination of C/N ratio control and substrate addition increased the net yield by 75% from 309 (CN10) to 540 (CN20 + P) kg ha^− 1 (120 days)^− 1. This 75% higher production concurred with (1) a lower inorganic nitrogen content in the water column, (2) a higher THB abundance supplying additional single cell protein to augment the prawn production, and (3) an improved periphyton productivity and quality.