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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.
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   

3.
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4.
This research studied the in vitro compatibility of Cherax quadricarinatus digestive proteases and crude enzyme extracts recovered from fish‐processing waste to evaluate their potential use as feed additives to increase digestion efficiency in decapod crustaceans. The sources of exogenous enzymes were: Pleoticus muelleri (Pm), Artemesia longinaris (Al), and Illex argentinus (Ia). The midgut glands of early (7.2 ± 0.34 g) and advanced juveniles (13.8 ± 1.49 g) of C. quadricarinatus were used for all the assays. The compatibility and synergy between crayfish and exogenous enzymes were evaluated through sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) electrophoresis and the hydrolysis of azocasein and four different meals. SDS–PAGE gels demonstrated that crayfish bands remained active when their enzymes were combined with the enzymes from Pm and Ia. An apparent enzymatic synergism was found when Pm and crayfish proteases were incubated together at pH 6 and 8 with azocasein (p ? 0.05). The ability to hydrolyze the different feed ingredients varied among the enzyme combinations assayed. Our findings suggest that fish waste has potential as a source of proteases, adding value to these processing residues and promoting a zero‐waste industry. Enzymes obtained from Pm and Ia are suitable to be used as food additives for crayfish. The results should be validated through feeding trials.  相似文献   

5.
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.  相似文献   

6.
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   

7.
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8.
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   

9.
The current study evaluated the effect of soluble dietary cellulose on growth, survival and digestive enzyme activity in three endemic, Australian freshwater crayfish species (redclaw: Cherax quadricarinatus, marron: C. tenuimanus, yabby: C. destructor). Separate individual feeding trials were conducted for late‐stage juveniles from each species in an automated recirculating freshwater, culture system. Animals were fed either a test diet (TD) that contained 20% soluble cellulose or a reference diet (RD) substituted with the same amount of corn starch, over a 12‐week period. Redclaw fed with RD showed significantly higher (P < 0.05) specific growth rates (SGR) compared with animals fed the TD, while SGR of marron and yabby fed the two diets were not significantly different. Expressed cellulase activity levels in redclaw were not significantly different between diets. Marron and yabby showed significantly higher cellulase activity when fed the RD (P < 0.05). Amylase and protease activity in all three species were significantly higher in the animals fed with RD (P < 0.05). These results indicate that test animals of all three species appear to utilize starch more efficiently than soluble dietary cellulose in their diet. The inclusion of 20% soluble cellulose in diets did not appear, however, to have a significant negative effect on growth rates.  相似文献   

10.
This work describes the profile of five proteases and four carbohydrases from the crustacean decapods Macrobrachium australiense (Holthuis), Scylla serrata (Forskal), Portunus pelagicus (Linnaeus), Penaeus esculentus, Penaeus plebejus (Hess) and Metapenaeus bennettae (Racck & Dall), feeding in the natural habitat, in order to provide an indication of their digestive capabilities. The results raised the following points. First, species from each family showed a particular suite of digestive enzymes. Second, the activity of cellulase from M. australiensis and S. serrata , using AZCL-HE cellulose as the substrate, was around 90% higher than that observed with AZO-CM cellulose. However, for P. pelagicus and P. esculentus , the enzyme activity was better with AZO-CM cellulose. Third, M. australiense displayed the highest ratio of amylase to protease activity. In contrast, Portunidae specie s, P. pelagicus and S. serrata showed the lowest ratios. Fourth, comparison of the laminarinase activity of M. bennettae and P. esculentus in October (Spring) and December (early Summer) showed a significant decrease in December. Finally, the wide distribution of digestive enzymes in these crustaceans may reflect different feeding habits and habitats.  相似文献   

11.
The digestive enzymes (proteases, carbohydrases and lipases) present along the alimentary tract of juveniles and adults of Diplodus puntazzo were studied. The data obtained showed a different distribution of the enzymatic activities in the different parts of the alimentary tract. Levels of enzymatic activity in the adults were higher than those measured in juveniles, suggesting that adults have a greater ability to digest larger pieces of food. The enzymatic pattern of D. puntazzo justifies its omnivorous habit and suggests an high potential for digesting vegetable polysaccharides. The results of this study suggest the need to adapt the diet to the digestive potential of this new farming species, thus contributing to the attainment of a product that is qualitatively more similar to the wild one.  相似文献   

12.
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   

13.
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   

14.
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   

15.
In the present study, digestive dynamics, measured through the changes in the in situ pH along the digestive tract, was evaluated along with the glycogen concentration in the digestive gland (DG) and the proteolytic enzyme activity of the gastric juice (GJ) (both acid and alkaline proteases) to obtain useful information that will allow for the understanding of the DG's function and the role that it plays as an extracellular digestive enzyme source and for energy storage, providing new information on the digestive physiology of Octopus maya. The results showed that pH along the digestive tract changed according to the postprandial time following the food transit. At the beginning, the pH on crop (St) was 5, changing to 6 when the food arrived. Similar changes were observed on the caecum (Ce) and DG. Glycogen from DG is used as a source of energy during digestion and recovered 8 h after feeding. Maximum activities of digestive gland GJ enzymes were observed 6 h after feeding, indicating that chyme enzymes are still active when they arrive at the DG's lumen. The presence of food in the digestive tract modifies the pH, which, in combination with GJ, favours the activity of the released enzymes of O. maya.  相似文献   

16.
This study was performed to determine the effect of starvation and delayed feeding on activities of digestive enzymes and alkaline phosphatase (ALP) of larval red swamp crayfish (Procambarus clarkii), so as to reveal the tolerance to prolonged starvation and the recovery of digestive enzymes after delayed feeding in larval and juvenile P. clarkii. In the control group, activities of trypsin and ALP increased significantly (p < .05) with day‐age and then kept constant at 24 days after hatching (DAH) and 10 DAH, respectively, whereas the activities of amylase and pepsin increased firstly then decreased with day‐age, and the activity of lipase increased firstly then decreased and then increased again during the development period of juvenile P. clarkii (1–31 DAH). In the group with continuous starvation (CS), activities of pepsin and lipase both decreased (p < .05) after fasting, and the activities of pepsin, lipase and trypsin in the groups with delayed feeding all increased (p < .05) and recover to the levels of the control group after food supply. However, the activity of amylase increased (p < .05) in the CS group, and it decreased to normal level after food supply. The ALP activity did not significantly (p > .05) vary after starvation, whereas it decreased in the groups with delayed feeding after 1 day of food supply, and then increased back to the level similar with the control group. Results from this study could provide information for diet preparation and feeding regime in larval and juvenile red swamp crayfish culture.  相似文献   

17.
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   

18.
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   

19.
Ontogenic development of the main enzymes and histological structure of digestive organs were studied in Jullien's golden carp (Probarbus jullieni) from hatching until 50 days after hatching (DAH). The larval fish were produced by artificial insemination and fed only Moina sp. till end of experiment. Body weight (mg) and total length (cm) of Jullien's golden carp increased exponentially and linearly. The results indicate the fish weight grew fast with increasing rate, while length increased at a constant rate over the studied period. Up‐regulation of acid protease was observed in newly hatched larvae and the specific activity gradually decreased with time. Trypsin specific activity was relatively stable within the first 35 DAH, while fluctuations in chymotrypsin were observed. Among these three proteolytic enzymes, acid proteases exihibited relatively high specific activity in newly hatched larvae, suggesting a role in yolk protein degradation. Alkaline proteases became more prominent with age and correlated with an abrupt decrease in acid proteases. Increased lipase‐specific activity appeared within 3 DAH and then gradually decreased with time, indicating the capacity to digest yolk lipid reserve. Amylase and cellulase‐specific activities changed in a similar manner, and the sensitivity to time was higher in amylase than in cellulase. The digestive organs and accessory organs developed around 3–5 DAH. However, intestinal histology was almost fully developed around 18 DAH. These findings should be useful for deciding the preferred timing for weaning, as well as on developing artificial diets referenced to the physiological changes of digestive enzymes.  相似文献   

20.
Overfeeding in aquaculture can lead to suboptimal growth and increased production costs. Red swamp crayfish, Procambarus clarkii, is one of the most noteworthy species cultured in China, but little information is available on the optimal feeding levels of this species, especially in ponds cultured with macrophytes. In this study, we tested the effects of five different feeding levels (20%, 40%, 60%, 80% and 100% satiation) of an artificial diet on growth performance and muscle composition of juvenile P. clarkii in 15 concrete ponds cultured with the macrophyte Hydrilla verticillata (three replicates for each treatment). The results showed that growth performance decreased only when feeding levels were below 60% satiation. Muscle composition analysis revealed that the moisture and ash contents of muscle did not vary significantly with feeding levels but that the lipid and protein contents of muscle significantly decreased when P. clarkii was fed to 40% satiation. Stable isotope analysis suggested a shift in crayfish diets to easily available H. verticillata when feeding levels decreased. With this study, we hope to encourage crayfish farmers to reduce feeding levels and increase natural food items such as macrophytes in cultured ponds to maximize crayfish yields and reduce production costs.  相似文献   

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