Potential of mixed culture of freshwater prawn (Macrobrachium rosenbergii) and self-recruiting small species mola (Amblypharyngodon mola) in rotational rice–fish/prawn culture systems in Bangladesh

The effects of different stocking densities of freshwater prawn (Macrobrachium rosenbergii) on its growth and production in relation to the presence of small self‐recruiting species mola (Amblypharyngodon mola) were investigated in modified rice fields after rice harvest at Mymensingh, Bangladesh. Keeping the stocking density of mola fixed at 20 000 ha^?1 in each treatment, four densities of freshwater prawn (treatments) were maintained: 10 000, 15 000, 20 000 and 25 000 ha^?1 respectively. The rice plots were limed (CaCO₃) and fertilized with urea, triple super phosphate and cowdung regularly. The prawns were fed daily with commercial pellets. Water quality parameters such as temperature, dissolved oxygen, transparency, pH, total alkalinity, inorganic nitrogen (nitrate, nitrite and total ammonia), chlorophyll a and orthophosphate were determined fortnightly. Numerical analysis of plankton communities was performed monthly. All water quality parameters were found to be within the suitable range for freshwater prawn culture, except high temperature, in the peak summer months. There was a homogenous abundance of plankton communities in all treatments throughout the experimental period. Mola started to breed in the second month of the original stocking with partial harvesting after the second month and continued until the final harvest. The total production of mola ranged between 124 and 152 kg ha^?1 during the 4‐month culture period. The average prawn survival ranged from 49% to 57% without any significant difference among treatments. Freshwater prawn production ranged from 294 to 596 kg ha^?1 with significantly higher production in the treatment where 20 000 ha^?1 freshwater prawn were stocked. This treatment also resulted in a higher net profit margin (74%), indicating that stocking at a combination of 20 000 ha^?1 freshwater prawn and 20 000 ha^?1 mola could be the optimum proposition for prawn–mola culture in modified rain‐fed rice fields after rice cultivation.     

Impacts of decentralized fish fingerling production in irrigated rice fields in Northwest Bangladesh

Rice field‐based fish seed production (RFFSP) has become established in parts of Northwest Bangladesh (NWB) as part of promoting improved rice‐based livelihoods. The impact of RFFSP on adopting households in terms of interactions of assets and other activities was assessed in a comparison of seed‐producing (RF; n = 60) and non‐seed‐producing (NRF; n = 58) households that were sampled randomly and ranked as poor, intermediate and better‐off. Adoption of RFFSP was not constrained by illiteracy of the household head, the size or ownership status of ponds, or lack of ownership of land or an irrigation pump. Poorer and intermediate households had smaller RF plots and lower production of fingerlings (kg per household) compared with the better‐off, although production efficiency (kg ha^?1) was higher. Restocking of fingerlings in RF household ponds increased productivity by 60% over NRF. Fish consumption of better‐off RF households exceeded NFR by 50%. Among the poor, seasonal benefits of income from sales and subsistence consumption of fingerlings were significant. Rice production in irrigated, and income in both irrigated and rain‐fed seasons was higher, and production costs lower, in riceplots producing fish than in rice‐only plots. Implications for supporting the innovation networks promoting and establishing RFFSP among rice growers, are discussed.     

Effects of all‐male,mixed‐sex and all‐female freshwater prawn in polyculture with major carps and molas in the fallow rice fields

This study was conducted to evaluate the effects of all‐male, mixed‐sex and all‐female freshwater prawn (Macrobrachium rosenbergii) in a polyculture with major carps (Catla catla and Labeo rohita) and self‐recruiting small fish molas (Amblypharyngodon mola) in the fallow rice fields of Bangladesh. There were three treatments with three replicates. All ponds were stocked with carps and molas plus either all‐male prawns (treatment MP), mixed‐sex prawns (MFP) or all‐female prawns (FP). Prawn, mola, catla and rohu were stocked 20 000, 20 000, 1750 and 750 ha^?1, respectively, in all treatments. The prawns were fed twice daily, starting at 8% body weight and gradually reduced to 3% body weight. The fish were fed in the morning with mustard oil cake and rice bran (1:2 ratios) at 3% body weight. Significantly higher production of prawns (697 kg ha^?1) was obtained in treatment MP, which yielded 34.7% and 56.2% more production than MFP and FP respectively. Significantly higher total production of 1620 kg ha^?1 and a higher benefit–cost ratio of 2.10:1 were also obtained in treatment MP. It can be concluded that an all‐male prawn culture is economically more viable than all‐female and mixed‐sex prawn cultures, along with other fish like major carps and the nutrient‐dense molas in the polyculture.     

Effects of including catla and tilapia in a freshwater prawn–mola polyculture in a rotational rice–fish culture systems

An on-farm trial was carried out from February to June 2006 to evaluate the growth and production performance of catla ( Catla catla ) and tilapia ( Oreochromis niloticus ) with freshwater prawn ( Macrobrachium rosenbergii ) and mola ( Amblypharyngodon mola ) in farmer's rice fields. In all treatments, 20 000 mola ha⁻¹ and 20 000 prawn ha⁻¹ were stocked. Besides, stocking included 2500 catla ha⁻¹ in treatment-I, 2500 tilapia ha⁻¹ in treatment-II and catla and tilapia at 1250 ha⁻¹ each in treatment-III . Prawns were fed in the evening with pellets at a feeding rate of 3–8% body weight (initially 8% and gradually decreased to 3%). Catla and tilapia were fed in the morning with a paste of mustard oil cake and rice bran at a feeding rate of 3% body weight. Significantly higher combined production of fish and prawn observed was 2142 kg ha⁻¹ in treatment-I. The benefit:cost ratio was found to be significantly higher in treatment-I than in treatment-II and there were no differences between treatments I and III. From the production and economic point of view, treatment-I was found to be the best proposition for the rotational rice–fish culture systems.     

Density effects of silver carp Hypophthalmichthys molitrix and catla Catla catla on the production system in all‐male freshwater prawn–finfish polyculture ponds

The effects of three different combinations of silver carp Hypophthalmichthys molitrix and catla Catla catla density on the production system in all‐male freshwater prawn–finfish polyculture ponds were evaluated in triplicate. The stocking density of silver carp and catla, respectively, were maintained at 2000 and 500 ha^?1 in treatment SC₂₀₀₀C₅₀₀, 1500 and 1000 ha^?1 in treatment SC₁₅₀₀C₁₀₀₀ and 1000 and 1500 ha^?1 in treatment SC₁₀₀₀C₁₅₀₀. Male freshwater prawn Macrobrachium rosenbergii and small fish mola Amblypharyngodon mola densities were fixed in all treatments at 12 000 and 20 000 ha^?1 respectively. Management practices were same for all treatments. Blue‐clawed male prawns were harvested twice during the 122‐day culture at 15‐day intervals before the final harvest. Plankton and macro‐benthos abundance and water quality parameters (except transparency and chlorophyll a) did not vary significantly (P>0.05) among treatments. Mean final weights of both silver carp and catla were decreased with the increasing of their own stocking density. The treatment SC₁₅₀₀C₁₀₀₀ resulted in 25–32% increased net production of silver carp plus catla (461 kg ha^?1) and 20–21% increased net production of all species combined (874 kg ha^?1) as compared with the other treatments, although the differences in production of prawn and mola among treatments were not significant.     

Effect of various medium compositions on survival and hatching rates of embryos of the giant freshwater prawn Macrobrachium rosenbergii cultured in vitro

SUMMARY: The effectiveness of in vitro embryo culture of the giant freshwater prawn Macrobrachium rosenbergii depended on the age of the embryos at the onset of culture and on the concentrations of various compositions in the medium. Embryos that started being cultured on day 0.5 after oviposition were more sensitive to variations in the medium compositions than those that started being cultured on day 10.5 after oviposition. An optimal NaCl level was essential for embryonic development, survival, hatching and survival of the newly hatched larvae. Variations of NaCl or KCl levels dramatically altered embryonic development, and variation of the MgCl₂ + MgSO₄ level significantly lowered survival of the embryos that started being cultured at the early stage of development. In contrast, no significant change in embryonic development was observed upon variation of the CaCl₂ level. Hatching of the embryos required the presence of NaCl and CaCl₂ but not KCl or MgCl₂ + MgSO₄. The ionic requirements of the newly hatched larvae differed from that of the developing embryos. Variations of NaCl, KCl or CaCl₂ but not MgCl₂ + MgSO₄ levels significantly influenced the survival of the newly hatched larvae.     

Low-cost diet for monoculture of giant freshwater prawn (Macrobrachium rosenbergii de Man) in Bangladesh

An experiment was conducted for 3 months in 12 experimental ponds, each of 30 m², with a view to develop a low‐cost diet for monoculture of Macrobrachium rosenbergii in ponds. Three experimental diets (30% protein) were formulated using fish meal, meat and bone meal, mustard oilcake, sesame meal and rice bran in different combinations partially replacing fish meal by meat and bone meal and sesame meal and assigned to treatments T₁, T₂ and T₃ respectively. A commercial golda feed (Starter‐III) was assigned to T₄ (reference diet). Each treatment had three replicates. Juveniles of M. rosenbergii (2.90±0.21 g) were stocked at the rate of 40 000 ha⁻¹. Prawns were fed three times daily at the rate of 10% and 5% of their body weight at the beginning and for the last 2 months respectively. The ponds were provided with aeration during the night using air pumps. The ranges of water quality parameters recorded in different ponds were: temperature 28.9–32.5°C, dissolved oxygen 5.1–8.1 mg L⁻¹ and pH 6.4–7.7. The results showed that the weight gain of prawns fed diet 1 was significantly higher (P<0.05) than those fed diets 2 and 3, but was not significantly different from those fed diet 4 (reference diet). The feed conversion ratio (FCR) values of diets ranged between 2.21 and 2.96 with diets 1 and 4 showing significantly lower (P<0.05) FCR values. The survivals (%) ranged between 68% and 78% with prawns fed diets 1 and 4 showing significantly higher survival. The production of prawn ranged between 921 and 1428 kg ha⁻¹ and diet 1 resulted in a significantly high (P<0.05) production. A simple economic analysis showed that diet 1 generated the maximum net profit of Tk 159 178 ha⁻¹. The results of the study showed that a diet containing 20% fish meal, 10% meat and bone meal, 15% mustard oilcake, 15% sesame meal, 35% rice bran, 4% molasses and 1% vitamin–mineral premixes may be recommended to the farmers for monoculture of M. rosenbergii in ponds.     

Greening the blue revolution of small‐scale freshwater aquaculture in Mymensingh,Bangladesh

Rapid development of small‐scale freshwater aquaculture in the Mymensingh district of north‐central Bangladesh has been linked to a ‘blue revolution’. Mymensingh is ranked first among districts of pond fish production in Bangladesh. Aquaculture in Mymensingh plays an important role in the local economy, contributing to food production, livelihood opportunities, income generation, poverty alleviation and social transformation. However, a number of challenges, particularly social, economic and environmental issues, will need to be overcome to translate its benefits effectively. We propose a conceptual framework for greening the blue revolution of aquaculture, which links social, economic and ecological aspects for promoting the importance of socio‐ecological, ecological‐economic and socio‐economic interactions. We conclude that active community participation, institutional collaboration and policy support are needed for greening the blue revolution of aquaculture in Mymensingh.     

Non‐permissive C6/36 cell culture for the Australian isolate of Macrobrachium rosenbergii nodavirus

Macrobrachium rosenbergii nodavirus (MrNV) that causes white tail disease (WTD) is an emerging disease that contributes to serious production losses in Macrobrachium hatcheries worldwide. Mosquito cell lines (C6/36) have been reported to support the growth of MrNV and used to observe the cytopathic effects (CPE) in infected cells. This study determined the susceptibility of C6/36 mosquito cells to the Australian isolate of MrNV in order to use fewer animals in further investigations. Different staining methods were used to observe MrNV viral activity in C6/36 cells. Typical cytopathic effects such as vacuolation and viral inclusion bodies were observed in infected C6/36 cells with H&E and Giemsa staining. With acridine orange, it was easier to detect presumptive MrNV messenger ribonucleic acid in the infected cells. Using neutral red staining to measure mitochondrial activity showed light absorption of infected cells maximized at day 4 (O.D. = 0.6) but was significantly lower (chi‐square = 41.265, df = 1, P < 0.05) than control groups (O.D. = 2) which maximized at day 12. Using trypan blue staining to count the number of cells with disrupted cell membranes, the maximum number of presumptively dead cells at day 8 (4 × 10⁵ cells) in infected treatments was higher than the control treatment at day 10 (1.8 × 10⁵ cells). However, TaqMan real‐time PCR did not confirm the replication of MrNV in the cells over 14 days. The mean viral copies and mean cycle times of positive samples were stable at 2.07 × 10⁴ and 24.12, respectively. Limited evidence of viral replication was observed during four serial passages. This study determined the mortality of the C6/36 cell line to the Australian isolate of MrNV but suggests limited patent replication was occurring. Trying different cell lines or adapting the virus to the C6/36 cells may be necessary to successfully replicate Australian MrNV in cell lines.     

不同鱼类混养组合与饲喂方式对鱼蚌综合养殖水体浮游植物群落结构的影响

利用三角帆蚌(Hyriopsis cumingii)、草鱼(Ctenoparyngodon idellus)、银鲫(Carassius gibelio)、鲢(Hypopth­almic­hthys molitrix)和鳙(Aristichthys nobilis)构建鱼蚌综合养殖系统, 通过155 d围隔(面积32 m²)实验检验两种鱼类组合(草鱼+鲫+鲢+鳙或鲢+鳙)和两种饲喂方式(投喂或不投喂配合饲料)对浮游植物群落结构的影响。采用2 × 2设计, 设4个处理: GISB-F(草鱼+鲫+鲢+鳙+投喂配合饲料)、GISB-NF(草鱼+鲫+鲢+鳙+不投喂配合饲料)、SB-F(鲢+鳙+投喂配合饲料)和SB-NF(鲢+鳙+不投喂配合饲料)。每个围隔内三角帆蚌、草鱼、鲫、鲢和鳙的放养量分别为20、15、5、5和5 ind。结果表明, 各处理围隔内浮游植物生物量平均值为3.7 × 10⁸~6.0 × 10⁸ cell·L^–1。改变鱼类组合和饲喂方式对浮游植物种类组成、优势种优势度、群落多样性、生物量以及浮游植物生物量中蓝藻的比例无显著影响, 但投喂配合饲料导致叶绿素a增加。浮游植物实验前期主要优势种为十字藻属(Crucigenia)和栅藻属(Scenedesmus)种类, 后期为平裂藻属(Merismopedia)和微囊藻属(Microcyslis)种类, 表明浮游植物群落演变具有明显的季节性特点以及优势种逐渐演化为蓝藻的规律。水温、氨态氮、总氮和高锰酸钾指数对浮游植物群落结构具有显著影响。各处理围隔内氨态氮、总氮和高锰酸钾指数均随时间延长而增加, 说明改变鱼类组合和饲喂方式不会影响围隔内蓝藻水华发生的趋势。

     

The androgenic gland and monosex culture of freshwater prawn Macrobrachium rosenbergii (De Man): a biotechnological perspective

Males of the freshwater prawn Macrobrachium rosenbergii (De Man) grow faster and reach a larger size at harvest than females of the species. It is thus obvious that culture of monosex all‐male populations would be economically advantageous. Sexual differentiation in crustaceans is regulated by the androgenic gland (AG), which plays a pivotal role in the regulation of male differentiation and in the inhibition of female differentiation. In M. rosenbergii, AG removal from immature males resulted in sex reversal, with complete female differentiation. Similarly, AG implantations into immature females lead to the development of the male reproductive system. Sex‐reversed M. rosenbergii animals were capable of mating with normal specimens to produce offspring. Early attempts in Israel and more recently, attempts in other countries to establish all‐male populations through manual segregation showed that for the production of monosex prawn populations to be economically feasible, intervention via the AG is probably required. However, a suitable biotechnology is still to be developed, and an androgenic hormone has yet to be identified in decapods. Three lines of aquacultural and biotechnological research and development are proposed for the future: (1) Establishment of monosex cultures through manual segregation, together with the application of selective harvesting and claw ablation, as well as examination of different monosex culture strategies under a variety of economic conditions. (2) Microsurgical intervention in the AG, leading to the development of functional neo‐females, which would subsequently be mated with normal males to produce all‐male progeny. (3) Elucidation of AG bioactive products to enable biochemical or molecular manipulation of sex differentiation.     

Evaluation and impact assessment of culture‐based fisheries to enhance fish yield in small reservoirs in Odisha State,India

The present study investigates the success of stocking fingerlings of Indian major carps ‐Gibelion catla (Hamilton), Labeo rohita Hamilton and Cirrhinus mrigala Hamilton – to enhance fish yield in 58 small reservoirs in Odisha State, India. Fish stocking and yield data were collected from State Fisheries Department, Odisha. The relationships between area, stocking density and fish yield of different size groups of reservoirs were assessed using the Pearson correlation coefficient (r). Fish yield increased significantly (p < 0.05, t‐test) from 204 kg/ha/year in 2012–13 to 323 kg/ha/year in 2013–14 due to adoption of CBF. The corresponding per capita fish production increased from 398 kg fisher^?1 year^?1 to 702 kg fisher^?1 year^?1 benefitting more than 8,000 fisher households. Reservoirs in the size group 100–500 ha showed the highest response of fish yield with respect to stocking of fingerlings. The size of fingerlings at stocking and area of the reservoir had greater impact on enhancing fish yield. Stocking had a profound positive impact on fish yield. This study forms a baseline evaluation of the impact of stocking on small tropical reservoirs in India. It also recommends management measures and discusses issues, and the way forward for sustainable fisheries enhancement in small tropical reservoirs in eastern India.     

Immunomodulatory effect of recombinant RNA‐dependent RNA polymerase protein of Macrobrachium rosenbergii nodavirus in giant freshwater prawn M. rosenbergii

The present study evaluated the role of recombinant RNA‐dependent RNA polymerase (RdRp) protein of Macrobrachium rosenbergii nodavirus (MrNV) in modulating the immune response and in reducing MrNV load in infected prawn. In the first experiment, prawns (25–30 g) were injected with recombinant RdRp protein (RP) at a concentration of 0, 1.0 and 10 μg, and immune parameters and expression of some immune‐related genes were measured up to 14 days post injection (p.i.). In the second experiment, early juveniles were injected with a similar dose of RdRp and animals were challenged by immersion with MrNV. The infection status was detected in muscles by nested RT‐PCR up to 21 days post challenge. Prawn injected with higher concentration of RP showed significantly higher total haemocyte count at different period post injection. Significant up‐regulation of immune‐related genes was observed within 24 h in prawn treated with lower dose of RP and after 7 days p.i. at higher level of RP injection compared with adult control. Most of the tested samples (63%) were found to be RT‐PCR positive for MrNV at 48 h of post‐immersion challenge. After 14 days, MrNV was detected only in control prawn, while both RP‐injected groups were MrNV negative. This study elucidated the potential viral load reduction role played by RdRP in MrNV‐infected prawn.     

Self‐confidence of anglers in identification of freshwater sport fish

Although several studies have focused on how well anglers identify species using replicas and pictures, there has been no study assessing the confidence that can be placed in angler's ability to identify recreationally important fish. Understanding factors associated with low self‐confidence will be useful in tailoring education programmes to improve self‐confidence in identifying common species. The purposes of this assessment were to quantify the confidence of recreational anglers to identify 13 commonly encountered warm water fish species and to relate self‐confidence to species availability and angler experience. Significant variation was observed in anglers self‐confidence among species and levels of self‐declared skill, with greater confidence associated with greater skill and with greater exposure. This study of angler self‐confidence strongly highlights the need for educational programmes that target lower skilled anglers and the importance of teaching all anglers about less common species, regardless of skill level.     

Use of artificial substrates to enhance production of freshwater herbivorous fish in pond culture

Two trials were conducted in mud‐bottomed concrete tanks to assess the potential of using artificial substrates to enhance fish production in ponds. Three substrate types were tested: bamboo poles, PVC pipes and sugarcane bagasse bundles. In one trial, periphyton was grown on the substrates in the absence of fish. In the second trial, masheer (Tor khudree Sykes) fingerlings were stocked at three densities. Results showed a significant effect of substrate type on fish growth (P≤ 0.001) and on net fish production (P≤ 0.05), with best growth in the tanks using the bamboo substrate. In the bagasse treatment, 100% fish mortality occurred. Highest extrapolated periphyton‐based gross fish yield (i.e. without feed inputs) was 450 kg ha^?1 90 d^?1 with PVC and 491 kg ha^?1 90 d^?1 with bamboo substrate. The best periphyton growth occurred on bamboo, followed by bagasse and PVC. Without fish, mean periphyton biomass during the culture period was 0.56–1.20 mg cm^?2 on bamboo [ash‐free dry matter (DM)], against 0.09–0.36 mg cm^?2 on PVC and 0.20–0.59 mg cm^–2 on bagasse. No clear effect of fish density or water depth on periphyton biomass could be seen. Only on bamboo, fish density seemed to have a negative effect on periphyton ash‐free dry matter and a positive effect on pigment content (chlorophyll‐a and phaeophytin). Periphyton from bamboo had a lower ash content (38–47% of DM) than from PVC (54–55% of DM) or bagasse (51–58% of DM). It is concluded that substrate type has a strong effect on periphyton productivity and composition, and on fish productivity. Good fish production was achieved without feed inputs. More research is needed to study the economic viability of periphyton‐based systems in the context of Indian aquaculture.     

Analysis of retinol, 3‐hydroxyretinol and 3,4‐didehydroretinol in North American farm‐raised freshwater fish liver,muscle and feed

Vitamin A (VA) is an essential micronutrient in fish, vital for reproduction, vision and immunity. Freshwater fish species store and use VA in the form of retinol (ROL), as well as uncommon forms such as 3,4‐didehydroretinol (DROL) and 3‐hydroxyretinol (3ROL). We developed and validated an HPLC method capable of measuring ROL, DROL and 3ROL in the feed and tissues of North American freshwater fish, for which little information on retinoid concentrations is available. DROL and ROL were higher than expected in both fish feed and fish liver (at 9.5–29.6 mg kg^?1 DROL and 26.9–79.2 mg kg^?1 ROL for feed; and 19.8–548.8 μg g^?1 DROL and 10.4–128.8 μg g^?1 ROL for liver). Interestingly, DROL concentrations were lower than ROL in fish feed, but often substantially higher in fish liver. Concentrations of ROL and DROL were similar to each other in muscle. 3ROL was detected in fish liver only. To our knowledge, this is the first publication to measure DROL concentrations in North American farm‐raised fish and commercial fish feed. Monitoring of not only ROL, but DROL and 3ROL as well, may be advisable to better assess the VA content of fish feed and tissue.     

The potential of mixed culture of genetically improved farmed tilapia (Oreochromis niloticus) and freshwater giant prawn (Macrobrachium rosenbergii) in periphyton-based systems

The production performance of genetically improved farmed tilapia (GIFT, Oreochromis niloticus) and freshwater prawn (Macrobrachium rosenbergii) in periphyton‐based systems were studied in farmers' ponds at Mymensingh, Bangladesh. Fifteen ponds (200–300 m² area and 1.0–1.5 m in depth) were used to compare five stocking ratios in triplicate: 100% GIFT, 75% GIFT plus 25% prawn, 50% GIFT plus 50% prawn, 25% GIFT plus 75% prawn and 100% prawn. Ponds were stocked at a total density of 20 000 GIFT and/or prawn ha^?1. Bamboo poles (mean diameter 6.2 cm and 5.5 pole m^?2) were posted in pond bottoms vertically as periphyton substrate. Periphyton biomass in terms of dry matter (DM), ash‐free DM and chlorophyll a were significantly higher in ponds stocked with prawn alone than in ponds with different combinations of GIFT and prawn. Survival of GIFT was significantly lower in ponds stocked with 100% GIFT (monoculture) whereas, that of prawn was significantly higher in its monoculture ponds indicating detrimental effects of GIFT on prawn's survival. Individual weight gains for both species were significantly higher in polyculture than in monoculture. The highest total fish and prawn yield (1623 kg GIFT and 30 kg prawn ha^?1) over 125–140 days culture period was recorded in ponds with 75% GIFT and 25% prawn followed by 100% GIFT alone (1549 kg ha^?1), 50% GIFT plus 50% prawn (1114 kg GIFT and 68 kg prawn ha^?1), 25% GIFT plus 75% prawn (574 kg GIFT and 129 kg prawn ha^?1) and 100% prawn alone (157 kg ha^?1). This combination also gave the highest economic return. Therefore, a stocking ratio of 75% GIFT plus 25% prawn at a total density of 20 000 ha^?1 appeared to be the best stocking ratio in terms of fish production as well as economics for a periphyton‐based polyculture system.     

Dietary supplementation of host‐associated lactic acid bacteria modulates growth,metabolic activities,and immune‐related gene expression in giant freshwater prawn,Macrobrachium rosenbergii

The present study was carried out to evaluate the dietary effects of host‐associated lactic acid bacteria on growth performance, metabolic enzyme activities, and immune response of Macrobrachium rosenbergii juveniles. To formulate the test diets, a control (Con) diet was supplemented with a commercial probiotic and three host‐derived bacteria Enterococcus faecalis (EC), Lactococcus lactis I (LC‐I), and L. lactis II (LC‐II), which were previously isolated from the gastrointestinal tract of adult individuals of M. rosenbergii. Juvenile M. rosenbergii (0.65 ± 0.008 g) were randomly stocked at 20 individuals/100 L of fiberglass tanks with three replications for each test diet. After 50 days, juveniles fed the diets LC‐I and LC‐II showed significantly higher (p < .05) weight gain, specific growth rate, and the lowest feed conversion ratio. The analyses of glutamic oxaloacetate transaminase and glutamic pyruvate transaminase in muscle and hepatopancreas revealed significantly (p < .05) reduced values in LC‐I fed juveniles. The total hemocyte count and phenoloxidase activity were significantly increased (p < .05) in LC‐I and LC‐II fed juveniles. The relative mRNA expression patterns of immune‐related α2‐M, LGBP, ProPO, Cu, Zn‐SOD, TG, PE, AKP, and ACP genes were significantly (p < .05) upregulated in juveniles fed with LC‐I followed by the diet LC‐II. Finally, the study suggests that the growth performance and immune response of M. rosenbergii can be improved through supplementation of host‐associated L. lactis bacteria for its higher production.