红螯螯虾XO-SG神经细胞的原代培养

本研究采用酶解的方法获得红螯螯虾眼柄XO-SG复合体的单个神经细胞,并依据显微观察对XO-SG神经细胞进行分类,同时利用Leibovitz's L-15等作为基础培养基离体培养解离的神经细胞。目的是建立虾类XO-SG神经细胞的分类标准并确定合适的培养条件,便于在体内外开展神经内分泌系统的调控研究。结果显示,根据神经细胞形态特点,红螯螯虾XO-SG神经内分泌细胞分为6种类型,不同类型的细胞在细胞大小以及显微结构上存在明显差异;建立了红螯螯虾眼柄XO-SG神经元的体外原代培养方法,细胞在改良的L-15培养基中存活状态良好,原代培养的神经细胞可以在体外存活14 d。离体培养过程中,不同类型神经细胞的再生速率存在差异,部分细胞在第2天就出现再生的轴突或树突。再生过程基本可以持续7 d,随后细胞开始萎缩凋亡。本研究为红螯螯虾眼柄神经细胞的分类以及利用神经细胞在体外开展虾类的内分泌代谢和调节机制研究提供了基础依据和研究平台。     

Intensification of redclaw crayfish Cherax quadricarinatus culture: II. Growout in a separate cell system

In the process of exploring ways to intensify crayfish culture, a growout system of individual cages (cells) was designed to determine the effects of gender and cell size on the growth of the red claw crayfish Cherax quadricarinatus. Cells of three different diameters—large (25 cm), medium (20 cm) and small (16 cm)—were used. When crayfish were stocked at a mean weight of approximately 10 g, growth rate of males was significantly higher than that of females. The growth rate of the males in the large cells was 0.31±0.14 g/day, while that of the females was 0.18±0.09 g/day. The size of the cell had significant influence on the weight of males. Male crayfish in the large and medium cells grew better than those in the small cells. When males were stocked at a higher mean weight (about 23 g), their mean weight after 206 days was higher in the large cells (69.28±15.72 g) than in the small cells (58.11±12.66 g), suggesting that the growth of large males was also affected by cell size. Regardless of cell size, male animals of this species grew faster than females under conditions of individual cells. This intensive culture method appears to present a powerful improvement in yields, by as much as two orders of magnitude, in comparison with communal cultures.     

Partial and total replacement of fish meal with soybean meal and brewer's grains with yeast in practical diets for Australian red claw crayfish Cherax quadricarinatus

Three feeding studies were conducted to evaluate the effects of total replacement of fish meal (FM) with a combination of soybean meal (SBM) and brewer's grains with yeast (BGY) in diets for two separate strains of juvenile Australian red claw crayfish. In Experiment 1, three practical diets were formulated to be isonitrogenous (40% protein) and isocaloric (4.0 kcal available energy/g diet) and contained either 25%, 10%, or 0% fish meal. Variable percentages of SBM (35%, 46.8%, and 79.8%, respectively) and BGY-35 (0%, 30%, and 5%, respectively) replaced the fish meal. In Experiments 2 and 3, four practical diets were formulated to be isonitrogenous (40% protein) and isocaloric (4 kcal available energy/g diet) containing 24% or 0% fish meal. Diet 1 contained 24% fish meal, 23% SBM, and 0% BGY-35. A variable percentage of SBM (56.75%, 47.75%, and 40.75%, respectively) and BGY-35 (10%, 20%, and 30%, respectively) replaced the fish meal in the remaining three diets.

In Experiment 1, after 8 weeks, juvenile red claw fed all three diets had no significant difference (P>0.05) in final weight, percentage weight gain, or survival, which averaged 7.90 g, 3848%, and 83%, respectively. In Experiment 2, after 8 weeks, juveniles fed all four diets had no significant difference in final weight, percentage weight gain, or specific growth rate which averaged 11.46 g, 977%, and 3.08%/day, respectively. Percentage survival was not significantly different among treatments and averaged 79%. In Experiment 3, after 8 weeks, juvenile red claw fed all four diets had no significant difference in final weight, percentage weight gain, or specific growth rate which averaged 16.22 g, 457%, and 2.34%/day, respectively. Percentage survival was not significantly different among treatments and averaged 98%.

These results indicate that fish meal and shrimp meal can be totally replaced with soybean meal and BGY in diets for juvenile red claw crayfish. This may allow for less expensive diets by red claw producers, which may increase profitability.     

Intensification of redclaw crayfish Cherax quadricarinatus culture: I. Hatchery and nursery system

Intensification of an indoor hatchery and nursery system for the Australian redclaw crayfish Cherax quadricarinatus (von Martens) (Decapoda: Parastacidae) was obtained by increasing the surface area available for the crayfish juveniles and by synchronizing the age of the hatchlings held in each tank. The former improvement was facilitated by distributing an artificial seaweed-like material throughout almost the entire volume of small (275 l) hatching tanks. As the number of egg-bearing females was increased from 3 to 8 per hatching tank, the number of juveniles per liter also increased to as many as 6.5 juveniles/l, without reaching an apparent upper limit. The hatchlings were kept in the tanks for 75 days from the day females were found to be gravid and then harvested and graded according to size. The average juvenile weight at harvest was 0.34±0.04 g. The weight distribution of the juvenile males was not significantly different from that of the juvenile females on the day of harvest, and in both the distribution was positively skewed.     

氨氮急性胁迫及其毒后恢复对红螯光壳螯虾幼虾相关免疫和代谢指标的影响

应用实时荧光定量PCR技术,结合生物酶和代谢产物测定,研究了氨氮急性胁迫对红螯光壳螯虾幼虾代谢及免疫系统的毒性影响及其毒后恢复情况。实验首先进行3 d的氨氮胁迫,取样后剩余虾移入曝气自来水进行7 d的毒后恢复实验。结果表明,3 d氨氮胁迫后,肌肉ACP、AKP、SOD活性表达均受到显著影响,随着氨氮浓度的升高酶活性分别降低,最高浓度组(16 mg/L)降低为对照组的76%、68%和62%。线粒体MnSOD、胞外Cu/ZnSOD的mRNA表达量也随着氨氮浓度增加而下降,最高浓度组降低至对照组的69%和68%。CAT、GPX活性以及GPX和GST的mRNA表达量变化不显著。肝胰腺中可溶性蛋白和甘油三酯含量随着氨氮浓度升高而降低,最高浓度组分别降低至对照组的72%和59%,AST活性在12 mg/L浓度组显著升高至对照组的134%。7 d恢复期过后,ACP和AKP活性以及各代谢指标恢复到正常水平;而SOD和GPX活性高于对照组。各抗氧化基因的表达量都不同程度高于对照组。实验表明,高浓度氨氮胁迫能抑制部分免疫相关酶的活性及基因表达,对免疫系统造成损害。氨氮胁迫下,红螯光壳螯虾动员蛋白质和脂肪来供能应对胁迫。7 d的恢复时间不足以让红螯光壳螯虾从胁迫中完全恢复,其肌肉仍处于轻度氧化应激状态。     

Characterisation of cellulase activity in the digestive system of the redclaw crayfish (Cherax quadricarinatus)

Endogenous cellulase activity was identified in the gastric fluid and digestive gland of the redclaw crayfish. Cellulase showed maximal activity from pH 4 to 5 and was stable for up to 2 h at 40°C. Cellulase activity in the digestive gland was unaffected by antibiotic treatment. Taken together these findings suggest a significant endogenous component for redclaw cellulase activity. Partial purification of cellulase activity was performed using anion exchange and gel filtration chromatography. One major and one minor band of activity were identified subsequently by SDS-PAGE and zymography. The molecular weight of the major band was estimated at 40 kDa while the minor band was estimated at 30 kDa. Redclaw cellulase enzymes demonstrated broad substrate specificity, hydrolysing polysaccharides containing β-1,4 and mixed β-1,4 and β-1,3 glycosidic bonds but showed a preference for soluble substrates. Hydrolysis products of cellodextrins of various lengths also showed that the enzymes liberated free glucose. Exposure of redclaw to antibiotics resulted in a dramatic decline in bacterial populations in the gastric contents (>90%) but only a 40% decline in cellulase activity.     

红螯光壳螯虾响应长期水体盐度胁迫的基因和代谢通路

为探究长期盐度胁迫条件下红螯光壳螯虾肠道基因表达和代谢通路的变化。实验采用Illumina Hiseq 2 500平台对0、5、10和15这4个盐度下养殖5周的红螯光壳螯虾的肠道组织进行了高通量测序。研究共获76 534个unigenes,通过与NR、NT、KO、Swissprot、PFAM、GO和KOG数据库进行比对,成功注释37 378个unigenes。通过引入FPKM(Fragments Per Kilo bases per Million fragments)来估算基因表达水平,基于NR和Pfam两个数据库的蛋白注释结果,448 362个unigenes在GO数据库得到注释。根据KO功能注释与Pathway的联系,9 483个unigenes在KEGG数据库被注释分类到34条通路途径。通过DEGseq进行基因表达差异分析,以盐度0为对照组,显著差异基因筛选条件设置为Q value<0.05且差异倍数|Fold Change|>2,盐度5、10和15组分别获得差异基因2 733、91和236个,其中盐度5组共有2 068个基因显著上调,665个基因显著下调。将所有差...     

Electrical stimulation of spermatophore extrusion in the freshwater yabby (Cherax destructor)

A technique for collecting spermatophores from male yabbies (Cherax destructor) is described. This technique consists of applying an electrical stimulus of between 5 and 10 mA and 40–50 Hz around the coxa of the fifth walking leg, and was found to have a success rate of 76% in 100 males tested. Furthermore, this approach enabled the collection of spermatophores from intersex individuals, indicating that intersex animals have the ability to function as males.

Using this technique, it was shown that spermatophore development is correlated with water temperature and that it is possible to elicit spermatophores from males in the non-reproductive season simply by raising water temperatures. The ability to non-invasively collect spermatophores from yabbies will facilitate the development of artificial fertilization techniques in this species.     

亚硝酸盐对红螯光壳螯虾不同组织免疫相关酶活性及超微结构的影响

应用透射电镜技术,结合生物酶测定,研究了水体中不同浓度亚硝酸盐胁迫下红螯光壳螯虾肝胰腺、鳃和肌肉组织中免疫相关酶的活性变化,以及对肝胰腺和鳃的形态学影响。结果显示,与对照组相比,亚硝酸盐胁迫下,3种组织的ACP、AKP、SOD以及GSH-PX的活性都显著降低(P<0.05);随着亚硝酸盐浓度增加,酶活力呈现降低的趋势;鳃组织Na+,K+-ATPase和Ca2+,Mg2+-ATPase的活性也显示出随亚硝酸盐浓度升高而降低的趋势。超微结构显示,随着亚硝酸盐浓度增加,鳃角质层受损、断裂;上皮细胞排列疏松、空泡化;细胞器变形;鳃腔内也出现空泡化现象,血细胞变形。肝胰腺上皮细胞排列杂乱无章,细胞裂解,空泡化;微绒毛受损、断裂,肝小管间距扩大、结缔组织变得稀薄,血细胞变形;高浓度组R细胞的脂滴减少,核膜解体,细胞膜破裂,空泡化加剧;F细胞的核糖体减少,空泡化加剧,内质网水肿。研究说明亚硝酸盐对红螯光壳螯虾3种组织的免疫相关酶活产生影响,并损伤肝胰腺和鳃的形态学结构,影响其生物学功能。     

Sperm maturation and capacitation in the open thelycum shrimp Litopenaeus (Crustacea: Decapoda: Penaeoidea)

Transmission electron microscopy was applied to sperm removed from males and females belonging to Litopenaeus vannamei, L. stylirostris and L. occidentalis. It was discovered that a region named filamentous meshwork (FM), located between the nucleus and the hemispherical cap, develops differently in these three closely related species. In L. vannamei, the FM is synthesized in the male reproductive system, but seems to complete its formation after mating. In L. stylirostris, the FM region was not present in spermatophores collected from males or in sperm from the thelycum. In L. occidentalis, the FM region is fully developed in male sperm. It is suggested that completion of the FM is required for acrosome maturation, and the process continues after mating in some species of Litopenaeus. In vitro induction of the acrosome reaction in sperm from males and females of L. occidentalis demonstrated for the first time that reactivity is significantly superior in sperm cells that have been attached to the open thelycum for some hours, as compared to sperm in males (prior to transfer). This finding suggests that matured sperm cells of L. occidentalis become capacitated to react against egg water after mating.     

饲料中非蛋白能源物质对红螯光壳螯虾幼虾生长、生理、生化指标的影响

在等蛋白质、等能量基础上,研究碳水化合物与脂类比例(CHO∶L)为10.75∶1、4.81∶1、2.66∶1、1.52∶1和0.87∶1的5组试验饲料对红螯光壳螯虾[初始体质量(1.72±0.01)g]相关生长、生理、生化指标的影响。8周试验结果表明,CHO∶L比例为2.66∶1时,红螯光壳螯虾的增重率、特定生长率和饲料利用率达到最高。高比例的CHO∶L(10.75∶1)和低比例的CHO∶L(0.87∶1)都会显著地抑制(P<0.05)红螯光壳螯虾的生长和饲料的利用。饲料脂肪水平为40～145 g/kg时,虾的脂肪酶和碱性磷酸酶活力显著升高(P<0.05),己糖激酶和丙酮酸激酶活力则呈显著降低趋势(P<0.05)。CHO∶L对虾胃蛋白酶活力影响显著(P<0.01),CHO∶L为2.66∶1和1.52∶1表现出比较高的活力,显著高于(P<0.05)其它试验组。碳水化合物为156.3～360.4 g/kg范围内,虾淀粉酶活力随饲料中碳水化合物的升高而显著升高(P<0.01)。红螯光壳螯虾增重率分别与饲料中碳水化合物和脂肪水平进行二次回归分析得出,红螯光壳螯虾对配合饲料中碳水化合物和脂肪的最适需求量分别为268.28和120.22 g/kg,相对应的CHO∶L为2.20∶1,且红螯光壳螯虾对碳水化合物的利用能力要高于对脂肪的利用。     

Influence of insoluble dietary cellulose on digestive enzyme activity, feed digestibility and survival in the red claw crayfish, Cherax quadricarinatus (von Martens)

Red claw (Cherax quadricarinatus) is a freshwater crayfish species with recognized potential for aquaculture. To better understand the digestive processes and nutritional requirements of red claw, we have examined the effects of dietary cellulose on (1) digestive enzyme activity and diet digestibility and (2) survival rate, feed conversion ratio and growth performance. In the first study, a reference diet (RF) and test diets consisting of 70% RF and 30%α‐cellulose or Fuller's earth were prepared. Analysis of digestive enzyme profiles revealed that amylase and cellulase activities in midgut gland (MG) extracts were highest in the red claw fed on a diet containing 30% Fuller's earth and lowest in those fed on a diet containing 30%α‐cellulose. Supplementation of the RF diet with either 30%α‐cellulose or Fuller's earth significantly reduced apparent dry mater (ADMD) and apparent protein digestibilities (APD). In the second study, a feeding trial was conducted using diets supplemented with different levels of α‐cellulose. A major finding was that dietary cellulose levels above 12% were correlated with significant reductions in survival rate, specific growth rate and feeding efficiency. Based on these findings, we suggest that although cellulase enzymes are present in the red claw digestive system there are no apparent nutritive benefits obtained by including insoluble cellulose in diets for this species.     

Experimental pond production of marron, Cherax tenuimanus (Smith) (Decapoda: Parastacidae)

Forty-two, 4-month pond trials were carried out on a large indigenous crayfish in south-western Australia — a candidate species for commercial aquaculture. Since growth rate and density are inversely related in this species the aim was to establish an intermediate range of density giving commercially acceptable values of growth rate and biomass. Survival over 4 months averaged 80.5% (30.7–100%) and was independent of density in the range 2–15/m²; low values (two below 50%) were due to oxygen depletion from overfeeding. The complex relationship between mean individual weight gain/4-month trial and initial mean individual weight was described indirectly using Mauchline's (1977) linear plot of log growht rate in length against initial length. A multiple regression equation accounted for 93.3% of the variability in log growth rate with 45.7% due to initial size, 40.6% due to seasonal water temperatures, 6.1% due to initial density and 0.8% due to feeding rate. Similar transformations were used to relate statistically production and biomass change to initial mean weight. Growth, production and biomass schedules were constructed for the most favourable temperature area of the south-west. A mean weight of 45 g at a biomass of 2100 kg/ha was predicted for the end of the first year of life and 111 g at 3175 kg/ha for the second year. Wide variability in individual weights represents a marketing problem. Plant material (poultry and lucerne pellets, compost) was supplied at rates of up to 1.0 kg/m² per 4 months as a substrate for detrital formation. Pollution from these materials generated limiting oxygen deficiencies.     

白斑综合征病毒对红螯光壳螯虾幼虾肝胰腺免疫酶活性及其超微结构的影响

利用生物化学方法和电镜技术,研究人工注射免疫多糖及WSSV对红螯光壳螯虾幼虾肝胰腺POD、LSZ、SOD、PO的活性变化及肝胰腺超微结构的影响。试验分对照组、实验组Ⅰ(注射WSSV)、实验组Ⅱ(注射免疫多糖)、实验组Ⅲ(注射免疫多糖48 h后注射WSSV)4组,结果显示,随着处理时间的增加,实验组Ⅰ与对照组相比POD、PO、LSZ活性均呈现明显降低趋势(P<0.01),而SOD活性呈现先升高后降低的趋势(P<0.01);实验组Ⅱ的螯虾4种酶活性呈现先升后降,与对照组相比酶活性增加(P<0.05);实验组Ⅲ4种酶活性均高于实验组Ⅰ(P<0.05),但与对照组相比SOD、POD、LSZ活性降低(P<0.01)。红螯光壳螯虾幼虾肝胰腺组织由肝小管组成,肝小管由基膜和上皮细胞组成。超微结构显示,对照组螯虾幼虾肝胰腺单层柱状上皮细胞的表面微绒毛排列整齐,各细胞器结构完整;实验组Ⅰ上皮细胞微绒毛受损、断裂,核膜解体,细胞核破裂,粗面内质网断裂;实验组Ⅱ上皮细胞粗面内质网核糖体增多;实验组Ⅲ与实验组Ⅰ相比,细胞核结构完整,粗面内质网肿胀,线粒体部分畸变。结果说明感染WSSV的幼虾肝胰腺形态结构受损,并进一步影响其生物学功能。人工注射免疫多糖能提高幼虾免疫相关酶活性,在一定程度上能抵抗WSSV的侵染。     

Effect of food restriction on female reproductive performance in the redclaw crayfish Cherax quadricarinatus (Parastacidae,Decapoda)

Aquaculture activity has grown remarkably in the last years, crustaceans being the most profitable products because of their high prices. Feeding costs represent a large portion of total operating costs in the aquaculture industry. In this context, the objective of the present study was to evaluate the effect of food restriction on the reproductive performance of redclaw crayfish Cherax quadricarinatus. Females at the onset of sexual maturity were stocked with males and were fed daily a formulated diet at 1.5% (control group) and 0.5% (restricted group) of their mean weight. The experimental period lasted 105 days. The percentage of ovigerous females and broods successfully hatched tended to be higher in restricted females compared with control females, but egg volume and weight did not differ between both experimental groups. However, the lipid concentration of rematuring ovaries was lower in restricted females than control females, suggesting that food restriction affects the amount of reserves transferred to the ovaries during vitellogenesis. The nutritional state of females was independent of the amount of food provided, as reflected by similar growth parameters and biochemical composition of the hepatopancreas in control and restricted females. Based on these results, we conclude that it is possible to reduce the feeding rate of C. quadricarinatus females to one‐third of its original value without affecting their reproductive performance and somatic growth, at least for a 105‐day period. This finding provides a useful tool for commercial producers to decrease production costs and improve water quality in culture systems.     

红螯光壳螯虾细胞自噬过程中自噬体与微管相互作用

昆虫方面研究提示自噬在病毒侵染增殖中发挥了重要作用,而虾类自噬研究报道极少,了解虾类细胞自噬将为虾病害免疫研究开辟新的思路。自噬相关蛋白LC3是自噬过程的标志性蛋白,存在于自噬体膜上,前期生物信息学分析发现,红螯光壳螯虾自噬相关蛋白LC3(CqLC3)和微管蛋白α-tubulin (Cqα-tubulin)具有互作关系。为深入揭示红螯光壳螯虾细胞自噬体的运输途径,本实验通过体外重组构建了蛋白表达载体pET-HISCqLC3和pET-GST-Cqα-tubulin,并诱导表达,利用亲和层析法分别纯化获得HIS和GST融合表达蛋白HIS-CqLC3和GST-Cqα-tubulin,利用GST pull-down实验验证发现,CqLC3与Cqα-tubulin存在相互作用。微管抑制剂长春新碱解聚微管后,利用MDC染色法检测自噬体发现,红螯光壳螯虾细胞微管解聚破坏后自噬体积累增多,细胞不能正常完成自噬反应,因此可知,红螯光壳螯虾细胞自噬体可通过CqLC3与微管相互作用,微管在红螯光壳螯虾细胞自噬过程中对自噬体的运输具有重要作用。本文首次揭示了虾类细胞自噬反应中自噬体的运输途径,研究结果为虾类细胞自噬的研究奠定了基础。     

Reducing aggression between freshwater crayfish (Cherax destructor Clark: Decapoda, Parastacidae) by increasing habitat complexity

The culture of decapod crustaceans occurs worldwide. Aggressive behaviour is common in many of the species, including crayfish. This is problematic when it physically damages stock and reduces quality. Numerous biological factors influence crayfish fighting behaviour but the influence of environmental factors is not well known. This study investigated the effect of habitat complexity on the agonistic interactions of Australian freshwater crayfish, more commonly referred to locally as ‘yabbies’ (Cherax destructor Clark). Solid objects that provided structure but not shelter were used to manipulate the complexity of the environment. The number, duration and dynamic of aggressive interactions within groups of animals were observed and recorded in simple and complex environments. Habitat complexity reduced both the number of agonistic interactions and the total time spent interacting. It is suggested that the structure in the environment distracts crayfish from the presence of others or physically blocks contact between them. These results extend our knowledge of crayfish social behaviour and may provide opportunities for reducing detrimental aggressive interactions in the aquaculture industry.     

Apparent nutrient digestibility of formulated diets by the Australian freshwater crayfish Cherax destructor Clark (Decapoda, Parastacidae)

Dry matter (DMD), protein (PD), ash (AD) and crude fibre (CFD) digestibility coefficients were determined for nine different diets fed to the Australian freshwater crayfish Cherax destructor Clark. Diets differed principally in the type and quantity of ingredients used to supply the protein component with fish, meat, soybean, snail, yabby and zooplankton meals comprising the main protein-based ingredients. DMD ranged from 71.8% (soybean meal 40%, Soy-40 diet) to a maximum of 91.4% (zooplankton-based diet). Protein digestibility coefficients were all high and ranged from 88.4% (Soy-0) to 96.0% (Soy-60). Protein digestibility did not appear to be influenced by the principal protein source. Diets that contained a high level of animal or plant-based protein were all highly digestible (PD, 94.1% for the yabby meal-based diet, 80.4% animal protein; PD, 95.2% for the Soy-60 diet, 80.2% plant protein). AD coefficients were highly variable and ranged from 17.3% (snail-based diet) to 73.2% (yabby meal diet). Crude fibre digestibility coefficients were as high as 57% (diet A30: fish/yabby/soybean meal-based diet). No apparent trend occurred in dry matter digestibility in relation to the ash or crude fibre components of the diets. The high digestibility coefficients obtained for a wide variety of diet-types suggests that C. destructor has a versatile digestive system which may reflect its natural polytrophic omnivorous feeding behaviour.     

Effects on growth,survival, body composition,processing traits and water quality when feeding a diet without vitamin and mineral supplements to Australian red claw crayfish (Cherax quadricarinatus) grown in ponds

To be profitable, producers must reduce diet costs, which can be as high as 80% of the variable costs of an aquaculture expense. As vitamin and mineral premixes represent a significant cost, eliminating addition of these premixes could reduce diet costs if no adverse effects were observed for growth and production parameters. A 105‐day feeding trial was conducted with juvenile Australian red claw crayfish (Cherax quadricarinatus) to evaluate the effects of growth, survival, body composition, processing traits and water quality when red claw were fed a supplemental diet containing 28% crude protein (CP) without vitamin and mineral premixes (and supplemented alfalfa hay) compared with red claw fed a diet (control diet) containing 42% CP, vitamin and mineral premixes, and with supplemented alfalfa hay, and compared with red claw only fed alfalfa hay when grown in ponds. Juvenile red claw (mean weight of 15.7 ± 1.0 g) were randomly stocked into nine 0.02‐ha ponds at a rate of 640 per pond (3.2 per m²), and each treatment was used in three ponds. There were two feedings per day, each consisting of one‐half of the total daily ration. At harvest, individual weight, percentage weight gain, specific growth rate, survival and total yield of red claw fed a control diet was significantly higher (P < 0.05) (83.0 g, 398%, 1.53% day^?1, 65.1%,and 1708 kg ha^?1 respectively) compared with red claw only fed alfalfa hay (44.9 g, 202%, 1.04% day^?1, 30.3% and 431 kg ha^?1, respectively), but not different (P > 0.05) from red claw fed the supplemental diet without vitamin and mineral premixes (76.2 g, 367%, 1.47% day^?1, 57.2% and 1378 kg ha^?1). There were no significant differences (P > 0.05) in feed conversion ratio (FCR) among treatments, which averaged 5.0 (based on prepared diet input). These results indicate that vitamin and mineral supplementation in a diet is not necessary when diet containing 28% CP and alfalfa hay are used in combination for pond grown red claw. These results may help reduce diet costs and possibly increase producers’ profits which might allow for industry expansion.     

Biochemical changes during vitellogenesis in the red claw crayfish,Cherax quadricarinatus (von Martens)

Redclaw crayfish (Cherax quadricarinatus) females at different stages of vitellogenesis were sampled to investigate variations in soluble protein, lipid and water content and in the amino acid and fatty acid composition of the hepatopancreas and ovaries. During vitellogenesis, the changes in the content of soluble proteins and lipids in the hepatopancreas and ovaries were dependent on both diet and the reserves from the hepatopancreas. However, in comparison to the ovary, the fluctuation of the amino acid composition in the hepatopancreas suggested that the protein resources mobilized from this organ was compensating for those gained from feeding. Changes in the fatty acid composition of the hepatopancreas showed limited compensatory function as for the quick accumulation of lipids in the ovaries. The proportional amounts of saturated fatty acids/mono‐unsaturated fatty acids/poly‐unsaturated fatty acids (PUFA) and the predominant fatty acids in both tissues indicated that the mobilization and utilization of fatty acids in freshwater species are different from that in marine species. Based on the redclaw's feeding habits, the commercial pellets used in this study may not be optimal, and a diet with less PUFA may suffice for its vitellogenesis and reduce the feeding costs.