Effects of Stocking Density on Nursery Production and Economics of the Freshwater Prawn,Macrobrachium rosenbergii

ABSTRACT

In temperate regions, post-larvae freshwater prawn, Macrobrachium rosenbergii, are grown to more advanced sizes in tanks prior to pond stocking. This intermediate stage of culture is referred to as the nursery period. Little research has been conducted on different management practices on juvenile prawn growth and survival during this 30-60 day period. Survival during the nursery stage has been highly variable and may be related to the cannibalistic behavior of juvenile freshwater prawn when cultured at high densities in the nursery. The objective of this study was to evaluate the effect of stocking density, relative to the provision of artificial substrate (number of prawns/m² of substrate), on growth, survival, and economic variables for freshwater prawn juveniles during nursery production. Post-larvae (0.01%0.00 g, n = 300) were stocked into nine 1900 L tanks, each provided with 20.5 m² of artificial substrate in the form of horizontal layers of black plastic mesh (10 mm) spaced 5 cm apart. Tanks were randomly assigned one of three prawn densities (215, 430, or 860 post-larvae/m² of substrate), which equated to 2.3,4.6 and 9.2 prawn/L, respectively. Juvenile prawn were fed a commercial trout diet (42% protein) at a percentage of body weight according to a feed rate table. Water quality was maintained using a flow rate of 8 L/min in each tank from a reservoir pond. Temperature was maintained at approximately 28°C using heat pumps. After 56 days there was no significant difference (P >0.05) in average weight of juvenile prawn stocked at the three densities (0 = 0.58%0.12 g, n = 9). Survival was significantly lower (P <0.05) for prawn stocked at 860 m² (62%) than in those stocked at 430/m² (78%) and 215/m² (94%), which were not statistically different (P >0.05). Even with reduced survival, the highest stocking density produced the greatest number of nursed juveniles based on both tank volume (5.5/l) and surface area (530/m²), at the lowest average cost.     

Applied Nutrition in Freshwater Prawn,Macrobrachium rosenbergii,Culture

ABSTRACT

The freshwater prawn, Macrobrachium rosenbergii, commonly called ‘scampi,’ is the most important culturable freshwater species of prawn with a fairly high growth rate, wide range of temperature (15-35°C) and salinity tolerance. The nutrients required by this species for growth and associated physiological functions are similar to those required by other crustaceans. Current data suggest that a digestible protein level of above 30 is required for maximum growth and protein efficiency. Ingredients such as mussel meat meal, squid meal, and shrimp meal serve as potential sources of protein in formulated diets. The complete quantitative requirements for all the essential amino acids for this prawn species have not yet been worked out. With respect to non-protein energy supply in the form of carbohydrate, studies indicated that scampi is capable of utilizing various carbohydrate sources efficiently. Dietary carbohydrate in the form of complex polysaccharides appears to be more effective as an energy source. Like other crustaceans, scampi also has limited ability to synthesize sterol from acetate and mevalonic acid. Quantitative estimates of the essential fatty acid requirements have been made in post-larval scampi. Data on vitamin and mineral requirements are scarce. Recent developments in diet formulation, practical feeding practices and the aquaculture potential in India have been indicated with emphasis on sustainable production.     

泼洒糖蜜对池塘养殖罗氏沼虾生长和水质的影响

将单口面积1.33~2.33hm~2、环境相似的6口罗氏沼虾养殖池塘分为2组,3口池塘投喂蛋白质水平为35.4%的饲料,且每日适量泼洒糖蜜(试验组),3口池塘投喂蛋白质水平为41.9%的饲料,不泼洒糖蜜(对照组),常规管理。养殖期间,每隔15d取水样检测氨氮和亚硝态氮含量。156d的饲养结果表明,对照组和试验组罗氏沼虾的产量分别为6600kg/hm~2和6427.5kg/hm~2,降低饲料中的蛋白水平结合泼洒糖蜜不影响罗氏沼虾的生长(P0.05),养殖效益亦无显著差异(P0.05)。但试验组池塘水中氨氮较对照组低54.0%,亚硝态氮低21.0%,泼洒糖蜜显著降低了池塘氨氮和亚硝态氮含量(P0.05)。     

Effects of Stocking Size and Density of Tilapia on Macrobrachium rosenbergii in Polyculture

Studies were conducted to determine the effect of stocking size and density of prawns in polyculture.
In one experiment, postlarval prawns (av. wt. 0.02 g) were stocked in six 0.02 ha earthen ponds at 35,00O/ha. Two ponds were stocked with tilapia fry (av. wt. 0.14 g) and two were stocked with tilapia fingerlings (av. wt. 30.1 g), each at 10,000/ha. Two control ponds had no tilapia. Tilipia stocking size had no effect on prawn growth. Mean weight of prawns after 70 days of culture ranged from a low of 4.5 g when cultured with tilapia fingerlings to a high of 6.6 when cultured in monoculture. Prawn survival was adversely affected by tilapia fry. Average prawn survival in tilapia fry ponds was 65% compared to 75% and 91%, respectively, in tilapia fingerling and monoculture ponds.
In a second experiment, postlarval prawns were stocked in nine 0.02 ha earthen ponds at 40,000/ ha. Six ponds were stocked with 30 g tilapia fingerlings, three at 5,000/ha and three at 15,000/ha. Three control ponds received prawns only. After 100 days of culture, prawn weight ranged from an average of 15.9 g in monoculture ponds to 11.5 g in polyculture ponds. Survival was highest (93.8%) in low density polyculture ponds. Survival was lowest (85.6%) in prawn monoculture ponds. Tilapia reproduction had a negative impact on shrimp production.     

Biochemical Changes in Freshwater Prawn Macrobrachium rosenbergii During Larval Development

Abstract.— Quantitative changes in the protein, lipid and carbohydrate were studied in the early larval stages of developing freshwater prawn Macrobrachium rosenbergii reared under fed and starved conditions to understand the relative importance of these nutrients in energy metabolism of the growing larvae. Larvae obtained from several females were stocked into three 250-L tanks at a density of 30 larvae/L. The feeding regime consisted of newly hatched Artemia nauplii. Protein was always the major organic constituent followed by lipids and then carbohydrates of both fed and starved larvae. Protein levels of both fed and starved larvae increased during development, suggesting an important role in morphogenesis. The decline of lipid during the larval growth that was more rapid for starved larvae, suggests a probable utilization of lipid as the major metabolic source of energy. Carbohydrates formed less than 5 and 2.4% of the larval dry weight of fed and starved larvae, respectively, suggesting their limited role in larval metabolism.     

Amino Acid Composition of Developing Larval Freshwater Prawn Macrobrachium rosenbergii

Abstract.— Amino acid profiles of freshwater prawn Macrobrachium rosenbergii were determined during early larval stages (I-IX) to provide some baseline biochemical information of the growing larvae. The larvae obtained from several females were stocked into three 250-L tanks at a density of 30 larvae/L. The feeding regime consisted of newly hatched Artemia nauplii and egg custard containing 5% cod liver oil. For each developmental stage, larval samples from each experimental tank were pooled, freeze dried and after acid hydrolysis, the quantification of amino acids was done by a reverse phase high performance liquid chromatography ( N = 2). The highest represented of the total amino acids were for glutamic acid and phenylalanine (with cystine) with ranges from 13.4–16.6 and 9.7–11.5%, respectively, whereas tryptophan (1.4–1.6%). methionine (1.4–2.7%) and histidine (2.9–4.2%) were relatively lower. The levels of the following essential amino acids did not significantly change during larval development: arginine, leucine, phenylalanine (plus cystine), threonine, tryptophan and valine. Despite statistically significant changes that were observed in levels of some amino acids, amino acid composition appeared to be relatively unchanged during the larval growth. The results may suggest that the amino acid requirements of the freshwater prawn is relatively constant during larval life and can be satistied by a suitable protein source that resembles the larval amino acid profile.     

罗氏沼虾的池塘养成

吴江市地处太湖东侧水网地带 ,有众多的淡水水域 ,水产养殖业历来发达。为了提高传统养殖渔业的经济效益 ,从 1 992年起着重推行罗氏沼虾池塘养殖规模经营。由于池塘养虾投资少、见效快、收益大、生产稳定 ,近十年来 ,各乡、镇的养殖面积逐年扩大 ,生产技术也渐趋成熟。现将罗氏沼虾的池塘养成主要技术措施介绍如下 :一、池塘条件1 .水源　　引用天然江河、湖泊等水源的水均可 ,但使用前必须了解 :水源是否被工业废水污染过 ;在罗氏沼虾生长高峰期 ,水的供应量是否有保证。2 .水温　　罗氏沼虾原产热带、亚热带 ,对低温的适应能力差。其适宜…     

Effects of Size and Age of Juvenile Freshwater Prawns Macrobrachium rosenbergii at Stocking on Population Structure and Production in Polyculture Ponds

Effects of size and age of juvenile freshwater prawns on their growth in polyculture ponds were investigated. Post-larvae were nursed at two commercial nurseries, during either 66 or 129 days, to final mean weights of about 0.25 and 0.5 g, for each age group. Nursed prawns were stocked in ponds at a density of 2/m² and polycultured with carps and tilapias for 148 days.
No significant effect of age or size, or their interaction, was detected in mean harvest weight and gross income, although small age effect was noted in survival and total yield.     

Impact of Substrate Physical Characteristics on Grow Out of Freshwater Prawn, Macrobrachium rosenbergii, in Ponds and Pond Microcosm Tanks

Two independent trials were conducted to evaluate the effects of different physical characteristics of substrate materials on growth and survival of freshwater prawn. In Trial 1, juvenile prawns (0.4 ± 0.2 g) were stocked at 123 prawns/m² of tank bottom into twenty‐one 18,000‐L fiberglass tanks managed as pond microcosms. Six substrate materials were chosen to allow comparisons of surface area, mesh size, color, and texture. A control treatment received no added substrate. There were three replicate tanks per treatment. Substrates were positioned vertically at a rate sufficient to increase the bottom surface area by 100%. Prawns were fed a 32% protein sinking diet according to a feed chart. After 110 d, there was no significant difference (P > 0.05) in survival among treatments, averaging 72.6% overall. Prawns in the control treatment (no substrate) had significantly lower (P ≤ 0.05) average weights (9.5 g), lower production (1342 kg/ha), and higher feed conversion ratio (FCR; 2.5) than those in substrate treatments, which were not significantly different (P > 0.05) and averaged 13.4 g, 2404 kg/ha, and 1.3, respectively. For Trial 2, the least expensive substrate material from Trial 1 (lightweight polyethylene bird netting) was compared with the substrate most commonly used in commercial production (heavyweight orange polyethylene safety fencing) under practical pond conditions. Juvenile prawns (0.8 ± 0.3 g) were stocked at 61,600/ha into six 0.04‐ha earthen ponds. Each was randomly assigned one of the two substrate materials, and there were three replications per treatment. After 101 d, there were no significant differences (P > 0.05) between treatments in terms of survival (91%), average weight (34 g), total production (2150 kg/ha), or FCR (3.1). In these studies, physical characteristics of the substrate materials had little impact. The lightweight netting represents a 68% cost savings compared to the currently recommended substrate material.     

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.     

Effects and Interactions of Stocking Density and Added Substrate on Production and Population Structure of Freshwater Prawns Macrobrachiurn rosenbergii

The effects and interactions of added artificial substrate with different stocking densities of prawns were evaluated. Juvenile prawns (0.2 ± 0.1 g) were stocked into 12 0.04-ha ponds at 60,000ha and 120,000/ha with and without substrate. Added substrate consisted of horizontal plastic mesh and strips of oyster netting sutlicient to increase available surface area 80%. There were no statistically significant ( P > 0.05) interactions between stocking density and presence of added substrate, allowing these main effects to be compared separately. Increasing stocking density produced a significant increase ( P < 0.01) in total production but a significant decrease ( P < 0.01) in average prawn size and production ( P < 0.05) of market size prawns (>20 g, -27%; > 30 g, -56%). Added substrate also produced a significant increase ( P < 0.05) in total production (18%). However, average prawn size was not decreased and production of marketable shrimp was increased (>20 g, 25%; >30 g, 19%). Feed conversion ratios were significantly decreased (P < 0.01) by the presence of substrate. Increased stocking density significantly increased ( P < 0.05) the percentage of males which were small males (SM) and decreased ( P < 0.01) the percentage of orange claw males (OC), but had no impact ( P > 0.05) on numbers of reproductive (RF) and virgin (VF) female morphotypes. Increased stocking density also produced a significant decrease ( P < 0.05) in average size of OC, RF, and VF morphotypes while the addition of substrate had no statistically significant impact (P > 0.05) on the number or size of different morphotypes. The mathematical relationship between available surface area and average prawn size should be determined to produce recommended inclusion rates for added substrate based on desired levels of total production, stocking rates, and optimum market sizes.     

Impact of Different Management Technologies on the Production, Population Structure, and Economics of Freshwater Prawn Macrobrachium rosenbergii Culture in Temperate Climates

In temperate zone ponds, maximization of total production without decreasing average harvest weight is of increased importance due to the relatively short growing season. Recent research on the freshwater prawn Macrobrachium rosenbergii has shown that techniques such as size grading juveniles and adding artificial substrate to the ponds can accomplish these goals, and their impacts appear to be cumulative. However, due to the greater investments required, private producers have been reluctant to adopt these practices. The studies involved in developing these independent technologies have been conducted over a number of growing seasons with their different environmental conditions. It is important that different production technologies being utilized by commercial producers be directly compared under standardized conditions. The objective of this study was to compare the previously recommended and widely used technology (39,200/ha; ungraded juveniles; no substrate) (Low Input) with an intensified version of that technology used by some producers (54,340/ha; ungraded juveniles; no substrate) (Medium Input) with a technology package developed through a series of research trials to maximize production (69,160/ha; graded juveniles; with substrate; phase feeding) (High Input) under standardized conditions. Each of the seven 0.04-ha ponds were randomly assigned to either the Low Input, Medium Input, or High Input treatment with two, three, and two replicate ponds per treatment, respectively. Juvenile prawns (ungraded 0.6 ± 0.3 g; graded 0.9 ± 0.3 g) were stocked at one of the three densities according to its randomly assigned treatment. Low and Medium Input ponds received no added substrate while artificial substrate was added to the High Input ponds a rate sufficient to increase available surface area by 50%. Low and Medium Input Treatments were fed a 32% protein sinking pellet according to a feeding table. High Input ponds were fed at rates 20% above the feed table recommendations. After 104 d, survival was significantly higher (P± 0.05) in the High Input treatment (92%) than in the Medium Input treatment (83%), with Low Input ponds being intermediate (88%). Compared to the Low Input technology, the Medium Input technology significantly increased (P± 0.05) total production but significantly reduced average weight, so that Production Stock Index (PSI) and production of marketable size animals (> 20 g) or premium size animals (> 30 g) was not significantly increased (P > 0.05). Compared to the original Low Input technology, the High Input treatment significantly increased (P < 0.05) production (92%), average weight (6%), Production Stock Index (PSI) (102%), market-able production (> 20 g) (140%), production of premium size animals (> 30 g) (130%), and feed efficiency (32%). The move from the Low Input technology to the High Input technology reduced breakeven costs by 13% based on operating costs and 22% based on total cost figures. In summary, adoption of the High Input technology appears to be biologically and economically justified if similar results can be obtained in commercial scale ponds.     

罗氏沼虾气单胞菌MrM0602株的分离和致病性研究

从濒死的罗氏沼虾体内分离到菌株M rM0602,经形态学观察及API 20E鉴定系统鉴定为嗜水气单胞菌。人工感染健康罗氏沼虾,100%致死剂量为1.0×104cfu/m l,半致死剂量(LD50)为3.16×103cfu/m l。测定菌株M rM0602的胞外产物对小鼠和新西兰大白兔红细胞的溶血活性,表明胞外产物对小鼠红细胞有微弱的溶血活性,对新西兰兔红细胞无溶血活性。胞外蛋白酶活力测定显示,菌株M rM0602胞外产物具有很高的蛋白酶活力,且耐热性很强,65℃仍保持较高活性。常规药物敏感性试验表明,菌株M rM0602对环丙沙星和恩诺沙星高度敏感。     

Effects of Diet and Organic Fertilization on Water Quality and Benthic Macroinvertebrate Populations in Ponds Used to Culture Freshwater Prawn,Macrobrachium rosenbergii

ABSTRACT

Effects of three diets: (1) complete diet; (2) supplemental diet (vitamin and mineral supplements not added); and (3) the supplemental diet with an adjunct organic fertilization regimen (using distiller's dried grains with solubles [DDGS]) on benthic macroinvertebrate populations and water quality in experimental ponds used to culture freshwater prawns, Macrobrachium rosenbergii were investigated. Benthic samples were taken from deep (1.5 m) and shallow (1.0 m) areas of each of nine 0.02-ha ponds every three weeks, using a 0.09-m² Ekman dredge. The abundance of gastro-pods, oligochaetes, total non-insects, chironomids, total dipterans, total insects, and total macroinvertebrates was significantly higher (P <0.05) in ponds receiving the complete diet, possibly due to lower predatory pressure by prawns or direct benefits of micronutri-ents. Total macroinvertebrate abundance was significantly decreased (P <0.05) in ponds receiving supplemental diet (with and without organic fertilization), possibly due to increased predation by prawns to supplement the nutrition not provided by the lower quality diet. Organic fertilization significantly increased (P <0.05) the abundance of oligochaetes and total macroinvertebrates. These data suggest that M. rosenbergii can adjust to reduced feed quality by increasing consumption of benthic fauna.     

The Effect of Biomass Density,Temperature, and Substrate on Transport Survival of Market-Size Freshwater Prawn,Macrobrachium rosenbergii

Abstract

After harvest, adult prawn are often transported for sales to live markets, such as ethnic Asian outlets, in major urban centers. Poor survival during transportation has hindered development and expansion of these markets. Methodologies to increase survival during transport could contribute to industry viability. Three independent trials were conducted. In the first trial, three biomass densities (25, 50 and 100 g/L) were evaluated in 100-L, open plastic containers aerated with pure oxygen and compressed air. Water quality analyses were performed prior to stocking. After 24 hours in the model transport containers, water quality analysis was conducted and all prawn were removed, determined to be alive or dead, and each group weighed and counted. There was no significant difference (P > 0.05) for prawn survival (overall mean 98%) among the three densities. Concentrations of dissolved oxygen and nitrite were not effected by hauling density (P < 0.05). Total ammonia-nitrogen and un-ionized ammonia-nitrogen concentrations increased (P < 0.05) as biomass densities increased, though values remained within what are considered tolerable ranges. In the second trial, the effect of added substrate and temperature on transport survival was evaluated with prawns stocked at the high density (100 g/L). Two water temperatures (21°C and 26°C) with and without substrate were evaluated in a 2 × 2 factorial with three replicate, 100-L model transport containers per treatment combination (12 containers total). Factorial analysis indicated no significant statistical interaction (P > 0.05) between the presence of substrate and water temperature on any measured variable. The main effects of substrate and temperature were then analyzed separately. The presence or absence of substrate had no significant impact (P > 0.05) on prawn survival. However, temperature had a highly significantly impact (P < 0.01) on survival; prawn survival at 21°C averaged 97% compared to 24% at 26°C. The third trial was a commercial verification trial in which 500 kg of live prawn were transported to New York from Kentucky. These data indicate prawn can be successfully transported at 100 g/L for 24 hours when temperatures are maintained near 21°C. Adding substrate to the transport tank appears to provide no benefit.     

Effects of Harvesting Methods on Population Structure,Growth and Yield of Freshwater Prawn,Macrobrachium rosenbergii,Cultured at Two Densities

Effects of harvesting methods (cull and batch) on population structure, growth, and yield of freshwater prawn, Macrobrachiurn rosenbergii, cultured at two densities (5/m2 and 10/m2) were evaluated. Females (67.4%) were more abundant than males (32.6%), but there was no effect of harvesting methods and stocking rates on sex ratio (P > 0.05). Mean survival rates ranged from 78.3 to 92.6%, being highest at a stocking density of 10/m2 and cull-harvested (P < 0.05), but were not different (P > 0.05) among three other treatments. After 196 days of culture, mean weights ranged from 25.3 to 29.9 g and were not significantly different from each other (P > 0.05). Mean weight of males was not hi her than that of f females (P > 0.05), except in one treatment (5/m² , batch harvest) where males were heavier (P < 0.05). Maximum specific growth rate (SGR) was recorded for prawns cultured at a density of 5/m² and cull-harvested (0.66%/day), followed by prawns at 10/m² and cull-harvested (0.58%/day). Minimum SGR was found for prawns cultured at 10/m² density and balch-harvested (0.43%/day). Maximum yield (2366 kg/ha and 2099 kg/ha) was recorded at the higher density (P < 0.05). Harvesting method had no effect on yield at any density (P > 0.05).     

Production of the Freshwater Prawn Macrobrachium rosenbergii Stocked as Juveniles at Different Densities in Temperate Zone Ponds1

Juvenile freshwater prawns Mucrobruchium rosenkrgii (mean wet weight = 0.75, 1986 or 0.17g, 1985) were stocked into 0.06–0.07 ha earthen ponds at densities ranging from 39,536 to 118,608/ha during two separate growing seasons. After growout periods ranging from 135 to 142 days, survival was from 54.3% to 89.9% (x = 77.0%). Mean prawn weight at harvest ranged from 15.0 to 44.3g and decreased with increasing stocking density. The larger stocking weight of prawns was associated with harvest weights that were 16.8 to 39.6% greater than those achieved with the smaller stocking weight at comparable stocking densities. Stocking of juveniles of the proper size and the effective management of the social structure of M. rosenkrgii appear to be critical to the success of intensive pond culture in temperate climates where the length of the growing season is restricted.     

Microbiological Quality of Farmed Tropical Freshwater Prawn (Macrobrachium rosenbergii de Man)

ABSTRACT

The objective of this study was to determine the microbiological quality of farmed giant freshwater prawn (Macrobrachium rosenbergii) collected from four freshwater farms located in Kerala (India). Microbiological counts on whole, deheaded, and deheaded and deveined prawn as well as on head and intestine were determined. Average counts (log₁₀ cfu g^?1) on whole prawn were 6.9 (total mesophilic counts (TPC) at 37°C) and 4.1 (psychrotrophic count at 7°C). The results indicated that the aerobic counts were within the acceptable limit. The levels of enterococci and faecal coliforms in farmed M. rosenbergii were high. There was an increase in the numbers of enterococci and Staphylococcus aureus after deheading. The major groups of bacteria comprising the flora of M. rosenbergii were Aeromonadaceae, Enterobacteriaceae and Pseudomonas. Farmed M. rosenbergii carried pathogenic bacteria such as Enterococcus spp., S. aureus, Aeromonas hydrophila, A. veronii biovar sobria and Clostridium perfringens. The results of the study suggest adoption of good farming and post harvest practices to improve the microbiological quality of farmed freshwater prawn.     

Protein Requirements of the Freshwater Prawn Macrobrachium rosenbergii Evaluated by the Factorial Method

The dietary protein requirement of the freshwater prawn Macrobrachium rosenbergii to obtain the maximum body protein retention was assessed by the estimated protein needed daily for maintenance (M) and body protein increment (G). The body protein increment was estimated by quantifying body nitrogen increments when the prawn was fed high‐protein diets composed primarily of casein. The protein required for maintenance was estimated by regressing weight gains in feeding experiments using graded dietary levels of casein. The true daily retention (R) or increase in body protein of the prawn corresponds to the sum of M and G. The values of M, G, and R determined in the present study were 3.86, 0.24, and 4.10 g/kg body weight/d, respectively. On the basis of the daily body protein increment and the net protein utilization of casein (58%), dietary protein requirement of the juvenile M. rosenbergii for maximum body protein retention was suggested to be about 7.1 g/kg body weight/d.