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1.
Redclaw crayfish (Cherax quadricarinatus, von Martens 1868) is a freshwater decapod crustacean with a number of biological and commercial attributes that make it an excellent aquaculture species. The redclaw aquaculture industry has been growing rapidly since the mid‐1980s in tropical and subtropical regions of the world. Redclaw aquaculture is mostly in extensive pond systems, but interest in developing more intensive systems is increasing. To support continued intensification, development of high‐quality practical diet formulations and information about redclaw nutrition requirements are necessary. A number of studies have determined optimum dietary protein and lipid requirements for juvenile redclaw. However, there is limited information on essential amino acid and fatty acid requirements. Several studies report the presence of various digestive enzymes that have been linked to the ability of the species to digest a wide range of dietary components. Furthermore, as in many other aquaculture species, there is a need to replace fishmeal with other protein sources. A number of studies explored the possibility of replacing fish meal with various terrestrial plant sources of protein and lipids and showed that redclaw can be offered diets containing low‐cost, plant‐based ingredients without compromising survival, growth and, to a certain extent, reproduction. Formulated diets containing less expensive, plant ‐ based ingredients will contribute to a more profitable and environmentally sustainable redclaw aquaculture industry. Finally, there is also a paucity of information on vitamin and mineral requirements of redclaw and little information on nutrient requirements of broodstock. For the redclaw aquaculture industry to thrive, we need to have a better understanding of nutrient requirements at all life stages.  相似文献   

2.
Redclaw aquaculture has developed at a rapid pace during the past few years, yet no specialized diet for the species has been developed. The present study was designed to evaluate whether soybean‐based diets containing either fishmeal (FM), poultry by‐product meal (PBM), ground peameal (GPM) or distillers dried grains with solubles (DDGS) meal as a protein source are suitable for redclaw aquaculture. Juvenile redclaw crayfish Cherax quadricarinatus (0.125±0.025 g) were stocked into 20 rectangular tanks at a stocking density of 12.5 m?2 for 8 weeks. Crayfish in four replicate tanks were maintained on one of five diets formulated to contain 35% crude protein and 7.1% lipids. Each 100 g of diet contained 25 g of protein from soybean meal (SBM) and 10 g of protein from the alternative protein sources mentioned above. A fifth treatment that did not receive feed was included to account for growth from natural productivity. There were no significant differences in survival (86–90%), growth (3.84–4.98 g animal?1) or feed conversion ratio (2.10–2.79) of crayfish among the four treatments (P>0.05). Survival and growth of crayfish in the treatment that received no supplementary feed were significantly less than those in treatments offered experimental diets. Results of the present experiment suggest that SBM‐based diets with PBM, FM, DDGS or GPM have similar effects on growth performance and survival of juvenile redclaw, C. quadricarinatus.  相似文献   

3.
Aquaculture of redclaw crayfish, Cherax quadricarinatus, is rapidly developing in tropical and sub‐tropical regions of the world. As the industry is still in its infancy, grow out diets are generally not formulated specifically for this species as there is limited data on nutrient requirements and the acceptability of various ingredients. Given the recent increases in the price of fish meal (FM), the use of alternative protein sources such as poultry by‐product meal (PBM) may be more cost effective. The present research evaluated the response of juvenile redclaw to practical diets utilizing PBM as a replacement for FM. Juvenile redclaw crayfish (0.45 g ± 0.01) were stocked into 24, 600‐L, outdoor round tanks at a density of 12.5 m?2. Tanks were supplied water from a watershed reservoir and maintained on a flow through regime. Crayfish in four replicate tanks were maintained on one of the six diets formulated to contain 260 g kg?1 crude protein and 70 g kg?1 crude fat which had previously demonstrated good growth under similar conditions. FM in the basal diets was replaced with PBM at various levels, on an iso‐nitrogenous basis, so that the diets contained 150, 120, 90, 60, 30 and 0 g FM kg?1 diet and 78, 105, 132, 158, 185 and 212 g PBM kg?1 diet, respectively. At the conclusion of the 56‐day growth trial, survival (>83%) and growth (>11.3 g or 2400%) of the crayfish were not significantly different among treatments. Based on these results, PBM appears to be a viable candidate as a replacement for FM in redclaw crayfish diets.  相似文献   

4.
The redclaw crayfish Cherax quadricarinatus (von Martens) accounts for the entire commercial production of freshwater crayfish in Australia. Two forms have been recognized, an ‘Eastern’ form in northern Queensland and a ‘Western’ form in the Northern Territory and far northern Western Australia. To date, only the Eastern form has been exported overseas for culture (including to China). The genetic structure of three Chinese redclaw crayfish culture lines from three different geographical locations in China (Xiamen in Fujian Province, Guangzhou in Guangdong Province and Chongming in Shanghai) were investigated for their levels and patterns of genetic diversity using microsatellite markers. Twenty‐eight SSR markers were isolated and used to analyse genetic diversity levels in three redclaw crayfish culture lines in China. This study set out to improve the current understanding of the molecular genetic characteristics of imported strains of redclaw crayfish reared in China. Microsatellite analysis revealed moderate allelic and high gene diversity in all three culture lines. Polymorphism information content estimates for polymorphic loci varied between 0.1168 and 0.8040, while pairwise FST values among culture lines were moderate (0.0020–0.1244). The highest estimate of divergence was evident between the Xiamen and Guangzhou populations.  相似文献   

5.
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6.
Juvenile redclaw crayfish, Cherax quadricarinatus, show non‐selective feeding behaviour when commencing feeding, but change to a dietary preference for plant material as they grow. This study aimed to find any ontogenic changes in digestive enzymes that might be associated with the change of diet. The enzymes in the digestive tract initially showed high levels of proteases and low levels of carbohydrases, but as the crayfish grew, the levels of proteases fell and the levels of the carbohydrases generally rose, in parallel with the increased preference for plant food. Cellulase was present in all free‐living stages. Dietary requirements of juvenile redclaw are probably quite similar to those of larger specimens.  相似文献   

7.
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.  相似文献   

8.
A growth experiment was conducted to determine the optimal dietary carbohydrate‐to‐lipid (CHO : L) ratio for the Australian redclaw crayfish, Cherax quadricarinatus (von Martens). Specimens were divided into five treatment groups and fed twice a day to apparent satiation with isonitrogenous and isoenergetic diets with dietary CHO : L ratios of 10.75:1, 5.99:1, 3.60:1, 2.18:1, or 1.33:1. Over the 8‐wk growth trial, redclaw crayfish fed the 2.81:1 and 3.60:1 diets exhibited better weight gain (WG), specific growth rate (SGR), and feed conversion ratio (FCR) than specimens fed the other diets (P < 0.05). Activities of hexokinase and pyruvate kinase were stimulated by elevated levels of dietary carbohydrate, whereas activities of lipase and alkaline phosphatase were stimulated by elevated levels of dietary lipid. Dietary CHO : L ratios significantly affected digestive enzyme activities (P < 0.05), except for trypsin (P > 0.05). On the basis of the analysis of growth, FCR, and costs of culturing redclaw crayfish, the optimal growth and costs occurred when the dietary carbohydrate and lipid levels were 290.10 g/kg and 80.70 g/kg, respectively, corresponding to a CHO : L ratio of 3.60:1. These results indicate that a CHO : L ratio of 3.60:1 is optimal for rearing redclaw crayfish and that this species uses carbohydrate more efficiently than lipid.  相似文献   

9.
New and viable species for aquaponics and integrated multi‐trophic aquaculture (IMTA) in freshwater systems can improve yields and sustainability of aquaculture. Freshwater crayfish species such as Astacus astacus and Pontastacus leptodactylus are omnivorous feeders and considered candidates for feeding on faecal matters in existing aquaculture systems. Feeding trials were conducted to determine growth response and RNA/DNA ratio in freshwater crayfish fed fish waste. Carapace length and wet weight were measured to determine the growth response. Juvenile A. astacus was fed faeces of hybrid striped bass (Morone chrysops × Morone saxatilis) and rainbow trout (Oncorhynchus mykiss), while adult P. leptodactylus was fed with two commercial pellet diets and pikeperch (Sander lucioperca) faeces. The nutritional composition of hybrid striped bass faeces was close to optimal diet composition of A. astacus, and crayfish showed significantly higher carapace growth, weight gain and weight gain per moult as the group fed rainbow trout faeces. The growth of P. leptodactylus was significantly lower in terms of weight gain and weight gain percentage per moult for crayfish fed on pikeperch faeces. Thus, this study can recommend a co‐cultivation of hybrid striped bass and A. astacus within one system, but cannot recommend co‐cultivation of P. leptodactylus with pikeperch. Additionally, this study showed controversial results of RNA/DNA ratio and weight gain of both crayfish species. Thus, RNA/DNA ratio cannot be approved for investigations on crayfish physiological status in controlled feeding experiments if animals are fed with an inadequate diet.  相似文献   

10.
Idiopathic lesions observed in redclaw freshwater crayfish, Cherax quadricarinatus (von Martens), from farms in northern Queensland, Australia, over a 4‐year period are described. Various idiopathic lesions were observed in the exoskeleton, antennal gland, mandibular organ, haemolymph vessel endothelium and enteric tissues of C. quadricarinatus collected for histopathological surveys, investigations of chronic mortalities or during other activities. The need for an increased use of histopathology in crayfish disease diagnosis is highlighted.  相似文献   

11.
Mobilization patterns of energy reserves during starvation are highly variable among crustaceans, and understanding this process is useful to satisfy the nutritional requirements of cultured organisms. The aim of this study was to elucidate the mobilization patterns on early and advanced juveniles—first free stage and one‐gram juveniles—of redclaw crayfish (Cherax quadricarinatus). A biochemical approach was used to analyse the organic carbon, total proteins, lipids and glycogen levels of the entire animal, and a histochemical approach was adopted to identify location of metabolites in the hepatopancreas and abdominal muscle. While starvation did not affect early juvenile protein levels, it showed a significant decrease in advanced juveniles. Histochemical analysis showed that lipid storage of hepatopancreas R cells was depleted near point of no return (PNR) and recovered after feeding. Glycogen storage was localized in the F cells of the hepatopancreas, and among muscle fibres of the abdomen, where after feeding, a pronounced accumulation was observed. Early and advanced juveniles of redclaw crayfish showed different patterns of consumption mainly related to the protein level, which was the most abundant reserve in advanced juveniles and the most consumed during starvation. Hepatopancreas R cells were confirmed as the principal lipid storage, whereas the abdominal muscle was the main glycogen storage. In crustacean aquaculture, the understanding of resistance to temporary feed deprivation is relevant to achieve an adequate feeding management, thereby avoiding the overfeeding and diminishing operating costs.  相似文献   

12.
Crustaceans are aquacultured both for food and as ornamental organisms. Pain and distress are not entirely understood in crustaceans, but the industry is moving towards requiring protection for the welfare of these animals during handling. In the present study, we evaluated the efficacy of clove oil as an anaesthetic for redclaw crayfish (Cherax quadricarinatus) as a model for freshwater crustaceans. We also studied how factors such as body weight and sex of redclaw could affect this efficacy. The whole experiment was replicated in two consecutive years. Redclaw juveniles were sorted into three size classes: small (<5 g), medium (5–12 g) and large (12–37 g). At least 10 males and 10 females from each size class were placed individually in water containing clove oil concentrations of 375 and 500 μl/L. Both concentrations induced rapid induction and recovery times, with 500 μl/L being the more effective concentration of the two. Induction and recovery times increased with the increase in crayfish size. No significant differences were found in induction and recovery times between male and female crayfish. Results suggest that clove oil is an effective anaesthetic for redclaw.  相似文献   

13.
Tilapia culture in rural communities in the state of Yucatan, Mexico, has been increasing in recent decades. Polyculture of tilapia with other more commercially valuable species provides an opportunity to substantially improve the economic yields of rural producers. The economic viability of implementing Nile tilapia with Australian redclaw crayfish in polyculture was analyzed using profitability indicators such as internal rate of return (IRR) and net present value (NPV). A bioeconomic model was developed to simulate three production densities, accounting for investment recuperation in time horizons of 5, 10 and 15 years. Simulations showed a notable improvement in profitability when farms adopt the polyculture strategy, particularly over the 5-year horizon. Nile tilapia with Australian redclaw crayfish polyculture shortens investment return time and buffers risk related to changes in tilapia sale price. Of the three studied polyculture combinations the optimum outcome was achieved with medium redclaw crayfish density.  相似文献   

14.
A stochastic bioeconomic model was used to estimate the production cost and risk factors affecting economic performance of juvenile redclaw crayfish, Cherax quadricarinatus, commercial nursery production, in a farm located in Baja California Sur, Mexico. At harvest, the biological submodel showed there is 95% confidence to obtain an average weight of 19.98 g, with 126,341/ha surviving organisms, representing 84% survival. Biomass was 2.5 t/ha, with a feed conversion ratio (FCR) of 0.98, reflecting the efficient adaptation of the species to culture conditions. The economic submodel showed that at Day 90, there is 95% confidence that the cost of producing a preadult will be US$0.090 or US$4.55/kg. With increasing demand and worldwide sale prices of US$9/kg, there is a potential market for 20–30 g redclaw reared in intensive lined ponds. Sensitivity analyses showed that the regression coefficients from a second‐order polynomial used for calculation of FCR associated with time (a2 and a1) were the most important parameters influencing the production cost. Mortality rate and parameters used to calculate individual weight also had considerable influence on production cost. The bioeconomic analysis contributes significantly to establishing the economic viability of the intensive three‐phase production system.  相似文献   

15.
A histopathological survey of commercial farms in Ecuador culturing redclaw crayfish, Cherax quadricarinatus (Von Martens), revealed the presence of different viral, bacterial and non‐infectious pathologies. A total of 536 animals from 27 different farms were analysed during a 3‐year period; 25, 154 and 357 specimens in 1995, 1996 and 1997, respectively. From the total sampled, a virus referred to as Cherax quadricarinatus bacilliform virus (CqBV) had a prevalence of 44% in animals examined during 1996 and 33% in 1997. A rickettsia‐like organism (RLO) was detected in five specimens sampled from three different farms in 1995. This RLO was detected in 36 and 12% of samples analysed in 1996 and 1997, respectively, and was the infectious agent most frequently associated with mortalities above 60%. Co‐infection by CqBV and the RLO was observed in 18 and 3% of the crayfish examined in 1997 and 1998, respectively. Five specimens out of 25 examined presented no sign of an infectious agent during 1995. The proportion of specimens testing negative by histopathology to known or suspected infectious agents was 25 and 32% in 1996 and 1997, respectively. Although different infectious agents were present in cultured crayfish, farms in general had overall survivals higher than 50% in most ponds. Other conditions observed included an intracellular prokaryotic organism, iron granules in the R and F cells of the hepatopancreas, different species of epibionts on the surface of the gills and body, and two cases of haemocytic enteritis. Two cases of serious mortality in different farms were associated with the presence of Cowdry type A inclusions, pyknosis, karyorrhexis and haemocytic infiltration in the stomach hypodermis and the antennal gland.  相似文献   

16.
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。  相似文献   

17.
The effect of eight diets with different protein‐to‐energy ratios (P–E ratio=10, 11, 14, 16, 18, 20, 22, 24 mg kJ?1) on reproduction of female redclaw crayfish Cherax quadricarinatus was tested under laboratory conditions. After 75 days, there was a significant effect of the P–E ratio on final weight, spawning females and the number of juveniles per female. Using the broken‐line and quadratic equations, optimal values for the P–E ratio were: 16.0, 17.1 and 16.0 mg kJ?1. The P–E ratio significantly affected protein and carbohydrate content and energy in the hepatopancreas. The broken‐line model indicated that the respective recommended values of the P–E ratio for these parameters were: 21.8, 16.7 and 18.6 mg kJ?1. The concentration of carbohydrates and energy in muscle tended to significantly diminish as the P–E ratio increased. From broken‐line regression analysis, the recommended P–E ratio was 16.6 and 20.2 mg kJ?1 respectively. No significant differences were found in survival, fecundity, vitellin content in eggs, protein and lipid content in muscle and lipids in the hepatopancreas. We concluded that, overall, a P–E ratio of 18±2 mg kJ?1 is optimal for reproductive activity of female redclaw crayfish.  相似文献   

18.
This study was conducted to evaluate the effects of dietary protein on digestive enzyme profiles, growth and tail muscle composition in the freshwater redclaw crayfish, Cherax quadricarinatus. Crayfish were fed five diets that consisted of a commercial crayfish pellet and experimental diets containing 13%, 18%, 25% or 32% crude protein (CP), for a period of 12 weeks. Analysis of digestive enzyme profiles from the midgut gland (MG) revealed a positive correlation between protease, amylase and cellulase activities and dietary protein level. For all treatments, carbohydrase activity levels (cellulase and amylase) were significantly higher than those detected for protease. As dietary protein was elevated, there was a general increase in specific growth rate (SGR), with the highest SGR (0.58 ± 0.06) values observed in crayfish fed the diet containing 25% CP. Feed conversion ratio (FCR) ranged between 5.84 and 6.97 and did not differ significantly among the treatment groups including the reference diet, with the exception of the low‐protein diet (13% CP) which showed an FCR of 9.31. Finally, regression analysis revealed a strong positive correlation between the level of dietary protein and CP content in the tail muscle (P=0.004; r2=0.99).  相似文献   

19.
In recent years, crayfish aquaculture industry has been developing rapidly in different regions of the world. Crayfish aquaculture is often carried out in dams, lakes and extensive pond systems. There is an increasing demand for crayfish juvenile in aquaculture sector. Therefore, it is important to know which factors affect reproductive efficiency in crayfish. In the present review, factors affecting the reproductive efficiency of crayfish are divided into two main sections, external and internal factors. Dietary lipids, phospholipids, highly unsaturated fatty acids, protein and amino acids, vitamins and carotenoids are important external factors affecting broodstock crayfish reproduction. In addition, various external (i.e. female size, stocking density, temperature, photoperiod, sex ratio) and internal (i.e. endogenous hormones) factors affect the reproductive efficiency in crayfish. This study reviews the present knowledge with the purpose of realizing the factors that are important to reach optimal crayfish nutrition, maturation and reproduction (i.e. pleopodal egg number and quality). This review will particularly be useful for crayfish farmers and crayfish hatchery units.  相似文献   

20.
This paper provides a review and summary of strain comparison and selective breeding work carried out on redclaw crayfish Cherax quadricarinatus (von Martens) at the Queensland Department of Primary Industries, Freshwater Fisheries and Aquaculture Centre, Walkamin. Redclaw crayfish are a highly marketable, environmentally tolerant, freshwater crayfish with a moderately fast, but variable, growth rate. Five strains of the species were assessed morphologically and in terms of age at maturity. A non‐replicated production trial was also carried out before two strains, from the Gilbert and Flinders rivers in North Queensland, were chosen to be part of an experimental selective breeding programme for improved growth. Initially, 14 families of each strain were randomly mated and grown out. At this point, a size‐related selection took place, with the largest animals from each family forming a selected line, and individuals from around the mean forming a control line. Within‐family selection and reciprocal mating between families was performed. Data were collected after each of two generations of growout and analysed by analysis of variance. Significant differences (P < 0.05) were measured between strains, sexes and between selected and control lines. Selected individuals grew 9.5% faster than the controls. Recommendations for selective breeding research involving freshwater crayfish are presented.  相似文献   

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