高蛋白配合饲料替代饲喂对拟穴青蟹肠道菌群的影响

为探明蟹公寓养殖模式下,高蛋白配合饲料替代杂鱼饲喂对拟穴青蟹菌群的影响,采用16S rRNA高通量测序技术,比较分析养殖过程中不同饵料组拟穴青蟹的肠道菌群结构。结果显示,各饵料组中优势菌群均为变形菌门、厚壁菌门、梭杆菌门和拟杆菌门,占操作分类单元总数85.84%以上。不同饵料组共有细菌操作分类单元(695个)占总数的18.92%,其序列数占总序列数的95.39%。主坐标分析显示不同饵料组肠道菌群的群落结构未产生显著分化。共现性网络分析显示,随养殖过程推进,微生物互作网络复杂度降低。功能预测分析显示,细菌次生代谢产物的生物合成、转运和分解代谢等功能主要在养殖前期出现显著性差异,而养殖后期饵料组间无显著性差异。试验结果表明,蟹公寓养殖过程中,不同饵料会对拟穴青蟹的肠道菌群造成影响。与杂鱼组相比,高蛋白配合饲料在维持肠道菌群多样性方面有一定优势,同时未显著影响肠道细菌群落结构和功能。     

温度对拟穴青蟹循环水养殖系统微生物群落结构的影响

为探究温度对拟穴青蟹(Scylla paramamosain)循环养殖水体中微生物群落的影响,深入理解环境因子与养殖水体微生物群落之间的相关性。在水温分别为18℃、22℃、26℃、30℃和32℃的循环养殖系统中进行拟穴青蟹养殖,采用16S rRNA高通量测序技术对不同温度下的养殖水体微生物群落组成进行分析。结果表明:(1) Alpha多样性指数显示5组水样中细菌群落多样性指数大小为t26t22t30t32t18,物种丰度大小为t22t26t32t30t18。温度可以导致养殖水体中微生物群落多样性发生变化,但并未发现二者之间直接的相关性。(2) 5种温度下的养殖系统中细菌群落共有31门、43纲、94目、185科和351属,变形菌门(Proteobacteria)为循环养殖水体中绝对优势菌门。在养殖系统水温为26℃时,养殖水体中氮磷污染物含量相对较高,其水中脱氮除磷菌属的相对丰度也显著高于其他4组。(3)由花瓣图和UPGMA聚类分析图进行相似性分析可知,水体微生物群落对温度的变化有着良好的响应, 5组水样的细菌群落结构总体相似性较低,其中最高温度32℃和最低温度18℃的水体中细菌群落结构最为相似。(4)水体中微生物群落结构和与环境因子的相关性分析显示,氮磷营养盐中的总磷(TP)和硝酸盐(NO3–-N)对水中微生物群落特征具有显著性影响,而温度是导致养殖水体中氮磷营养盐差异化的主要原因。上述研究结果初步解释了温度对拟穴青蟹循环养殖水微生物群落的作用机制,为下一步深入研究拟穴青蟹循环水养殖系统中环境变化与微生物的相互关系提供参考。     

北方吊笼养殖刺参肠道及其养殖环境菌群结构特征及其相关性分析

为探究北方吊笼养殖刺参(Apostichopus japonicus)肠道及其养殖环境菌群结构的关系,本研究基于高通量测序技术全面解析刺参肠道和养殖环境菌群结构和功能特征,并初步探讨刺参肠道及其养殖环境菌群相关性。结果显示,刺参肠道菌群丰度和多样性均显著高于养殖水体(P<0.05)。刺参肠道及养殖水体主要优势菌门均隶属于变形菌门(Proteobacteria)和拟杆菌门(Bacteroidetes),二者存在13个相对丰度大于0.1%的共有核心菌属。此外,肠道菌群具有一定的独立性,其特异性菌群主要隶属于厚壁菌门(Firmicutes)和绿弯菌门(Chloroflexi),以芽孢杆菌属(Bacillus)、乳酸杆菌属(Lactobacillus)、海泥海球菌属(Halioglobus)、Lutimonas和Woeseia为代表。基于KEGG代谢通路数据库,共注释到300条三级代谢通路,其中146条存在极显著差异(P<0.001)。刺参肠道菌群差异代谢通路主要表现在代谢方面,具体表现为碳水化合物消化吸收、蛋白质消化吸收和鞘脂类代谢。研究表明,刺参肠道菌群种类与其养殖水体呈高度相似性,但相对丰度存在显著性差异。本研究结果可为北方刺参吊笼健康养殖提供一定的理论依据。     

斑点叉尾肠道及其养殖环境菌群结构分析

为探究健康斑点叉尾(鱼回)肠道及其与养殖池塘水体中菌群结构的关系,采用16S rDNA高通量测序方法和生物信息学分析手段考察其肠道和养殖水体中微生物群落组成和多样性。多样性指数分析结果表明,斑点叉尾(鱼回)肠道菌群丰度和菌群多样性均较养殖水体低。斑点叉尾(鱼回)肠道中有69.57%的运算分类单元与水体中一致,水体中优势菌群主要为变形菌门、放线菌门和蓝藻门,而肠道中的优势菌群为拟杆菌门、梭杆菌门和厚壁菌门,说明肠道和养殖水体中的优势微生物种群的组成和丰度无明显的相关性,肠道中菌群组成有一定的独立性,其优势菌群结构几乎不受养殖环境菌群的影响。PICRUSt预测细菌表型发现,斑点叉尾(鱼回)肠道中以厌氧菌和革兰氏阳性菌为主;从生物膜形成和致病潜力表型可知,肠道和水环境中均存在大量条件致病菌。试验结果表明,池塘养殖健康斑点叉尾(鱼回)肠道微生物中的优势益生菌主要为鲸杆菌属和拟杆菌属,平均相对丰度高达36.60%和15.82%。本试验将为斑点叉尾(鱼回)的健康养殖和益生菌的筛选提供理论依据。     

高通量测序分析血根碱对中华鳖肠道菌群结构的影响

为研究血根碱对中华鳖(Trionyx sinensis)肠道菌群多样性及丰度的影响,选取480只初始体重为(31.75±7.20) g的中华鳖,设置添加0的对照组(RS1)和添加50 (RS2)、100 (RS3)和150 mg/kg (RS4)的3个实验组。实验结束后,提取中华鳖中肠组织的总DNA,进行16S rRNA V3-4区基因组测序。结果显示,实验组的总操作分类单元(Operational taxonomic units, OTUs)数量显著高于对照组,肠道菌群复杂度及丰富度较对照组有明显增加。肠道菌群结构组成分析发现,RS1与RS2结构较为接近,而RS1与RS3、RS4较远。在门分类水平上,变形菌门(Proteobacteria)和衣原体门(Chlamydiae)是优势菌群;在属分类水平上,螺杆菌属(Helicobacter)占绝对优势。通过比较发现,实验组中螺杆菌属丰度较对照组显著下降,而不动杆菌属(Acinetobacter)、乳杆菌属(Lactobacillus)和双歧杆菌属(Bifidobacterium)丰度均有明显上升。研究表明,在饲料中添加适量的血根碱(100~150 mg/kg)能有效提高中华鳖肠道菌群多样性及丰富度,并能改善肠道菌群结构。     

南移池塘养殖仿刺参肠道菌群结构分析

本文基于MiSeq高通量测序技术对南移福建池塘养殖仿刺参(Apostichopus japonicus)肠道菌落结构进行分析。结果表明,仿刺参前肠(1 C_1)、中肠(1 C_2)和后肠(1C_3)测得的分类操作单元(OTUs)分别为424、444和414;三组样品的菌群物种丰度没有较大差别,但优势菌种存在较大差异;优势菌群方面,后肠的优势菌群为Haliea属和乳球菌属(Lactococcus)(分别占后肠总菌数的11.97%和10.37%),而前肠和中肠的优势菌群均是乳球菌属和芽孢杆菌属(Bacillus),两者在前肠菌落中的占比分别为27.91%和6.08%,在中肠中的占比分别为33.24%和6.97%。在重复性方面,三组样品的菌落组成都有重叠,重叠率为74.35%,其中前肠与中肠相似度较高,菌株种类有90%以上重叠。本文研究为仿刺参肠道益生菌的开发利用提供基础资料。     

健康和患病卵形鲳鲹肠道菌群结构的差异

为研究病害发生后卵形鲳鲹肠道菌群结构的差异及其与养殖环境的关系,分析不同样品中的菌群组成和细菌多样性。实验采用Illumina HiSeq高通量测序技术和生物信息学分析手段,分别构建了健康鱼水样、患病鱼水样、健康鱼肠道、患病鱼肠道和饵料颗粒5个样品中菌群的16S rRNA基因测序文库。研究表明,与健康鱼肠道细菌组成相比,患病鱼肠道中螺旋体门相对丰度显著升高,厚壁菌门和拟杆菌门相对丰度显著降低;患病后肠道中的细菌种类仅为健康鱼肠道细菌种类总数的54.94%;健康卵形鲳鲹肠道菌群中有73.46%的可操作分类单元(OTUs)与水体样品中OTUs一致,有70.58%与饲料样品一致,而患病后分别只有17.98%和38.95%的OTUs与水体和饲料样品一致。健康卵形鲳鲹肠道中黑海弧菌的相对丰度为17.19%,患病后该菌的相对丰度大幅提高,达到78.90%;健康鱼肠道中鳆发光杆菌占比54.53%,患病鱼肠道中不含鳆发光杆菌。健康和患病鱼肠道菌群种类组成类似,但存在一定差异,病害的发生会导致肠道细菌多样性显著降低。健康鱼肠道菌群与养殖环境和颗粒饲料中菌群组成关系密切,而患病后鱼肠道细菌多样性受环境中菌群的影响较小。黑海弧菌在患病鱼肠道中的大量增殖可能是引起其患病的重要原因。     

福建吊笼养殖仿刺参肠道菌群结构分析

该研究基于Mi Seq高通量测序技术对福建霞浦海域海上吊笼养殖仿刺参（Apostichopus japonicus）肠道菌落结构进行分析。结果表明,仿刺参前肠（2H₁）、中肠（2H₂）和后肠（2H₃）测得的分类操作单元（OTUs）分别为124、116和78。3个组织样品菌群的物种丰度和优势菌种存在较大差别,其中前肠的物种丰度最高,为2.38,中肠其次,为2.22,后肠最低,为1.24。优势菌群方面,后肠的优势菌群为Formosa和乳球菌属（Lactococcus）（分别占细菌总数的87.38%和7.74%）,而前肠和中肠的优势菌群均是乳球菌属和芽孢杆菌属（Bacillus）,两者分别占前肠中细菌总数的59.68%和11.8%,在中肠中的占比分别为62.45%和12.07%。在重复性方面,后肠中发现的细菌在前肠和中肠中都有发现,而前肠和中肠分别发现6个和4个特有菌群。 

     

长江鲟幼鱼黏液、肠道内容物及其养殖水体的微生物菌群结构和潜在病原菌分析

长江鲟(Acipenser dabryanus)为中国特有鱼类,已被国际自然保护联盟(IUCN)列为极危级(CR)物种。通过Illumina高通量测序技术,探究了长江鲟幼鱼黏液、肠道内容物及其养殖水体的微生物菌群组成、多样性及动态变化,以期为长江鲟幼鱼健康养殖和病害分析提供参考依据。结果显示：养殖水体微生物多样性最高,黏液次之,肠道内容物最低。黏液和肠道内容物微生物菌群结构更为相似,且可与养殖水体微生物菌群区分开来。在门水平,黏液和肠道内容物均以放线菌门、变形菌门和厚壁菌门为主;养殖水体则以变形菌门、拟杆菌门和厚壁菌门为主。研究还发现7种可能的病原菌在养殖水体和黏液中富集,当鱼体处于应激状态或养殖环境恶化时,可能导致病害发生。BugBase表型预测分析发现,长江鲟幼鱼黏液、肠道内容物及其养殖水体中存在革兰氏阴性菌和阳性菌。其中肠道内容物的优势菌群为革兰氏阳性菌,占比超过60%;黏液和养殖水体的优势菌群均为革兰氏阴性菌,占比分别为60%和70%。在氧气需求方面,黏液和肠道内容物以好氧菌为主,养殖水体以好氧菌和兼性厌氧菌为主。     

池塘养殖牙鲆肠道和环境菌群结构对益生菌制剂的响应

为研究益生菌制剂对池塘养殖牙鲆(Paralichthys olivaceus)肠道及环境菌群结构的调控效果,采用高通量测序技术和生物信息学分析手段构建牙鲆肠道、养殖水体、饵料和池塘底泥的16S rDNA基因测序文库,分析不同样品中菌群组成和多样性在益生菌制剂调控过程中的变化趋势.结果显示,添加益生菌制剂后,池塘底泥和牙...     

Development of nursery culture techniques for the mud crab Scylla paramamosain (Estampador)

Cannibalism is one of the main causes of mortality in the culture of the mud crab Scylla paramamosain, particularly in the early post‐larval and juvenile stages when the densities of hatchery‐reared crabs may be very high before stocking into ponds or release into the wild for stock enhancement. In a series of experiments investigating cannibalism mitigation, the influence of stocking density, the effectiveness of sand substrate, brick and shell shelters and feed type were compared in culture of crabs from instar 1 for short nursery periods of 15–30 days. Inclusion of brick and shell shelters significantly increased survival over sand substrate alone. However, inclusion of shelters did not affect growth rates. In scaled‐up nursery production in lined‐ponds, with shelters, live Artemia biomass and fresh chopped shrimp or tilapia were found to be equally effective feeds for juvenile crabs stocked at a density of 70 m⁻² from instar 1 and grown for 30 days [52–66% survival, 21.6–24.6 mm carapace width (CW)]. In an extended nursery period for a further 30 days, crabs of 22 mm CW, stocked at 30 m⁻² in the same ponds, attained a final size of 34.5–36.2 mm CW with a survival of 64.3–67.0% using the same feeds.     

Improved techniques for rearing mud crab Scylla paramamosain (Estampador 1949) larvae

A series of rearing trials in small 1 L cones and large tanks of 30–100 L were carried out to develop optimal rearing techniques for mud crab (Scylla paramamosain) larvae. Using water exchange (discontinuous partial water renewal or continuous treatment through biofiltration) and micro‐algae (Chlorella or Chaetoceros) supplementation (daily supplementation at 0.1–0.2 million cells mL⁻¹ or maintenance at 1–2 millions cells mL⁻¹), six different types of rearing systems were tried. The combination of a green‐water batch system for early stages and a recirculating system with micro‐algae supplementation for later stages resulted in the best overall performance of the crab larvae. No clear effects of crab stocking density (50–200 larvae L⁻¹) and rotifer (30–60 rotifers mL⁻¹) and Artemia density (10–20 L⁻¹) were observed. A stocking density of 100–150 zoea 1 (Z1) L⁻¹, combined with rotifer of 30–45 mL⁻¹ for early stages and Artemia feeding at 10–15 nauplii mL⁻¹ for Z3–Z5 seemed to produce the best performance of S. paramamosain larvae. Optimal rations for crab larvae should, however, be adjusted depending on the species, larval stage, larval status, prey size, rearing system and techniques. A practical feeding schedule could be to increase live food density from 30 to 45 rotifers mL⁻¹ from Z1 to Z2 and increase the number of Artemia nauplii mL⁻¹ from 10 to 15 from Z3 to Z5. Bacterial disease remains one of the key factors underlying the high mortality in the zoea stages. Further research to develop safe prophylactic treatments is therefore warranted. Combined with proper live food enrichment techniques, application of these findings has sustained a survival rate from Z1 to crab 1–2 stages in large rearing tanks of 10–15% (maximum 30%).     

拟穴青蟹vasa基因cDNA的特征分析与性腺特异表达

vasa蛋白属于DEAD家族蛋白,是一种RNA解旋酶,在生殖细胞的分化中具有重要作用。本研究从拟穴青蟹卵巢中克隆得到vasa基因cDNA全长(将其命名为Sp-vasa),Sp-vasa序列长度为2 944 bp,其中开放阅读框(ORF)长度为1 899 bp,编码632个氨基酸,具有DEAD-box家族蛋白的7个高度保守的结构域。半定量RT-PCR结果显示,Sp-vasa只在卵巢和精巢中特异表达,在其它组织则未检测到表达。由此可见,vasa属于拟穴青蟹性腺特异表达基因。因此,Sp-vasa基因可有望作为有效的分子指标研究拟穴青蟹原始生殖细胞的起源、迁移以及生殖腺的发生。     

Apparent digestibility of selected feed ingredients in diets formulated for the sub-adult mud crab, Scylla paramamosain, in Vietnam

The present study was conducted to explore the potential to incorporate local plant-based feed ingredients into diets formulated for the mud crab species, Scylla paramamosain , commonly exploited for aquaculture in South-east Asia. Four test ingredients (defatted soybean meal, rice bran, cassava meal and corn flour) were incorporated at 30% or 45% inclusion levels in a fishmeal-based reference diet and used in digestibility trials where apparent digestibility coefficients (ADCs) for experimental diets and test ingredients were determined. Generally, high ADC values were obtained using diets containing 30% soybean meal or rice bran. By contrast, the lowest ADC values were obtained for the diet containing 45% cassava meal [70.9% for dry matter (ADMD); 77.1% for crude protein (ACPD) and 80.2% for gross energy (AGED)]. Similar trends were observed when ADC ingredient (I) digestibilities were compared. Specifically, the highest ADCI values were obtained for soybean meal when used at a 30% inclusion level (87.6% ADMDI; 98.4% ACPDI and 95.6% AGEDI) while the lowest ADCI values were obtained using cassava meal at a 45% inclusion level (53.8% ADMDI; 60.2% ACPDI and 67.3% AGEDI). Based on the current findings, we propose that soybean meal and rice bran could be considered for incorporation into formulated diets for S. paramamosain .     

Induced out-of-season spawning of the mud crab, Scylla paramamosain (Estampador) and effects of temperature on embryo development

Treated with combined bilateral eyestalk ablation and maintenance of water temperature at 22.5±1.5 °C, mud crab Scylla paramamosain females with mature ovaries were induced to produce eggs outside the natural spawning season in subtropical southern China. Newly extruded eggs from a crab were incubated in vitro at 10, 15, 20, 25, 27, 30, 35 °C, respectively, and the embryonic development was closely monitored. Abnormal cell division was observed at temperatures 10 and 35 °C. At 15 °C, development remained at the gastrula stage by day 32 post‐spawn, at which time the experiment was terminated. Hatching of in vitro incubated eggs occurred between 20 and 30 °C. An increase in incubation temperature from 20 to 25 °C reduced the incubation duration by 14 days, 2.6 times of that measured for a similar 5 °C increase from 25 to 30 °C. Embryonic development of S. paramamosain was divided into stage 0–10, and the duration of each stage was recorded for each incubation temperature. The information obtained allows accurate prediction of hatching time of female crabs incubated under variable temperatures. Larvae hatched from in vitro incubated eggs were reared to reach first juvenile crab stage and their dry weights were similar to those of larvae hatched naturally.     

南美白对虾养殖环境及其肠道细菌多样性分析

为了探讨南美白对虾(Penaeus vannamei Boone)肠道及其养殖环境中细菌种群组成和分布,采用Illumina miseq测序平台,基于16S r RNA基因的序列测定结果,对南美白对虾肠道及其养殖池塘底泥、水体中细菌的种群结构进行分析。结果显示,在南美白对虾肠道、养殖池塘底泥、水体分别检测到206、265和270个细菌属,其中,有90个属在3个样品中均可检测到,底泥和水、底泥和虾肠道、水和虾肠道中检测到的共有细菌属分别为146、128和119个,表明养殖池塘底泥、水和肠道中细菌存在密切的相互作用。在底泥、水和虾肠道样品中丰度大于1%的优势菌属分别有20、17和10个;底泥、水体和虾肠道中丰度最高的细菌均为一种分类未明的细菌属,丰度分别为23.08%、37.13%和42.22%。除此之外,底泥中主要优势细菌属分别为假单胞菌属(Pseudomonas)(5.77%)、Ohtaekwangia(4.79%)和狭义的梭菌属(Clostridium)(3.88%);水体中主要优势细菌属分别为土壤杆菌属(Sediminibacterium)(6.64%)、Spartobacteria genera incertae sedis(3.95%)和GPIIa(3.20%),而虾肠道中主要优势细菌属分别为假单胞菌属(Pseudomonas)(14.57%)和不动杆菌属(Acinetobacter)(6.54%)。在底泥、水和肠道中分别检测到3、6和6个潜在致病细菌属,丰度最高的细菌属分别是假单胞菌属(5.77%)、黄杆菌属(Flavobacterium)(0.77%)和假单胞菌属(14.57%)。在底泥、水和肠道中检测到的益生菌可分别分配至8、6和7个细菌属,其中有5个属在3个样品中均可检测到。聚类分析显示,养殖池塘底泥、水体和南美白对虾肠道细菌种群中丰富度位于前20的分类操作单元(OUT)在聚类树的位置存在明显不同。研究结果进一步加深了对健康南美白对虾肠道细菌种群及其与养殖环境中细菌种群互作的理解,为益生菌制剂的研发提供了新的线索。     

拟穴青蟹ANT2基因在不同温度和盐度条件下的应激表达

采用qRT-PCR技术, 对不同温度(10℃, 15℃, 20℃, 25℃)以及低温(10℃, 15℃)和盐度(10, 35)联合作用下拟穴青蟹(Scylla paramamosain)(甲壳长3.7~5.8 cm, 体质量80~100 g) ANT2基因的表达进行了检测。结果表明: 在4个温度下肝胰腺、肌肉、鳃中ANT2基因表达量依次为低、中、高, 存在组织表达特异性。随着温度降低, ANT2基因总体上趋低表达, 但在15℃时ANT2基因在肌肉(1~12 h)和鳃中均显著高于20℃(P<0.05)。该结果提示, ANT2基因与能量代谢相关, 且在一定低温下被诱导表达, 可能参与低温胁迫的应答。相同低温下, 3种组织中ANT2基因在盐度10的表达量通常高于盐度35的(P<0.05), 说明低温下低盐环境有利于提高青蟹体内代谢, 增强耐寒能力。     

饲料蛋白质水平对拟穴青蟹幼蟹生长性能、体成分和消化酶活性的影响

用蛋白质水平分别为31.45%,36.37%,41.55%,46.13%,51.72%和56.86%的6种等能饲料,对初始体重为(11.86?0.11)mg的拟穴青蟹(Scylla paramamosain)幼蟹进行为期3周的养殖实验,考察饲料蛋白质水平对拟穴青蟹幼蟹生长性能、体成分以及消化酶活性的影响,以期获得拟穴青蟹幼蟹饲料蛋白质的适宜添加量。结果表明,饲料蛋白质水平对拟穴青蟹幼蟹的成活率影响不显著(P0.05);幼蟹的增重率和特定生长率随饲料蛋白质水平的提高先显著升高(P0.05)后稍有下降,最大值出现在蛋白质水平为51.72%的实验组;随着饲料蛋白质水平的提高,幼蟹粗蛋白质含量显著升高(P0.05)后趋于稳定,粗脂肪含量显著降低(P0.05),灰分含量先显著升高(P0.05)后显著降低(P0.05),水分含量则没有显著变化(P0.05);随着饲料蛋白质水平的提高,幼蟹蛋白酶活性显著升高(P0.05),淀粉酶活性显著降低(P0.05),各组脂肪酶活性也有显著差异(P0.05),但没有明显的变化规律。本研究条件下,饲料蛋白质水平在41.55%~56.86%,拟穴青蟹幼蟹均表现出较好的生长率,增重率和蛋白质水平的回归分析表明,幼蟹饲料蛋白质适宜水平为49.03%。     

Effect of different forms of Artemia biomass as a food source on survival,molting and growth rate of mud crab (Scylla paramamosain)

An experiment was conducted to evaluate the effect of different forms of Artemia biomass as a food source on survival, molting and growth rate of mud crab Scylla paramamosain. Instar 1 crablets with a mean weight of 0.0082 ± 0.0007 g were reared both individually and communally and fed with different diets consisting of fresh shrimp meat (control feed), live Artemia biomass, frozen Artemia biomass and a dried Artemia‐based formulated feed for 40 days. The highest survival was obtained for crablets receiving live Artemia (92.5% and 75.8%) followed by the groups fed with frozen biomass (90.0% and 47.5%), the control feed (72.5% and 24.2%) and the dried Artemia‐based diet (60.0% and 21.7%) for individual and communal cultures, respectively. The intermolt period, the total number of moltings and the growth rate, which were determined on individually reared crabs, showed the same pattern as for survival. The results suggest that crab performance decreased in the following order: live Artemia>frozen Artemia > fresh shrimp meat > dried Artemia‐based formulated feed. Live Artemia biomass proved an ideal feed for nursery of Scylla paramamosain crabs. Frozen Artemia biomass may be an alternative in times of shortage. Our findings illustrate the high potential for local utilization of Artemia biomass in Vietnam for reliable production of mud crab juveniles.     

Reproductive performance and offspring quality in mud crab (Scylla paramamosain) broodstock fed different diets

A 2-month feeding trial was conducted toevaluate the reproductive performance andoffspring quality of mud crab (Scyllaparamamosain) females fed either a mixture offresh food items (squid, shrimp, trash fish andArtemia biomass) or two experimentaldiets developed for penaeids. Before testinitiation, mud crab females with an averageindividual wet weight of 200–300 g wereacclimated for 2–3 days and reared together inone concrete tank of 2.0 × 0.5 × 8 m untilspawning. After spawning, the spent spawnerswere unilaterally eyestalk ablated and randomlydivided (20 animals/treatment) over three tanksof the same size and subjected to the dietarytreatments. Spent spawners were used toeliminate the effect of feeding history.There were only minor differences inreproductive performance between dietarytreatments. No differences were observed in theduration of the latency period from eyestalkablation to spawning. Fecundity was onlymarginally higher for the broodstock fed thecontrol diet. Also egg quality seemed onlyslightly affected by the treatments. Egghatching rates were slightly higher in crabsfed the formulated diets compared to thosecrabs fed the fresh diet. The onlystatistically significant difference (p < 0.05) observed however was in egg hatchingrate between the control diet and diet A2. Incontrast, the crabs fed the fresh diet producedstronger larvae as determined by a starvationtest.We therefore conclude that artificial dietsresulted in reproduction success comparable tothe use of fresh food. The nutritionalcomposition of the artificial diets couldhowever be improved in order to produce larvaeof optimal quality. Based on our researchfindings, the protein level and n-3 HUFA levelin the diet warrants further investigation inthis respect.