Effect of Bacillus subtilis on growth development and survival of larvae Macrobrachium rosenbergii (de Man)

A feeding experiment was conducted to investigate the effect of Bacillus subtilis bacterium, on larval growth and development rate of Macrobrachium rosenbergii (de Man) during February 28 to April 8, 2005 in University Putra Malaysia hatchery. Newly hatched larvae of M. rosenbergii were reared with two dietary treatments consisting of newly hatched Artemia salina nauplii with B. subtilis (10⁸ cells ml⁻¹), and newly hatched A. salina nauplii without B. subtilis carried out in triplicate in 60‐L aquarium (50 L⁻¹). After trial, the larvae that fed B. subtilis‐treated Artemia naupli were found to have higher survival and a faster rate of metamorphosis than larvae that were fed with nontreated Artemia naupli. There were significant differences between B. subtilis‐treated Artemia naupli and nontreated Artemia diet in larval growth and development rate of metamorphosis (P < 0.05). Larval survival after 40 days was significantly greater (P < 0.05) in the B. subtilis‐treated groups (55.3 ± 1.02) compared with the nontreated groups (36.2 ± 5.02%).     

Fecundity changes in Macrobrachium rosenbergii (de Man) during egg incubation

Abstract. For a study of the fecundity of Macrobrachium rosenbergii , a total of 117 berried females were sampled from ponds. Fecundity was found to vary from 1216 to 89747 eggs for prawns measuring 9.0cm to 15.8cm total length and weighing 6.22 to 45.80g. The relationship between fecundity (EN) and total length (TL) was found to be EN = 0.001876 TL^6.3617.
The average egg number/g total body weight for prawns having orange, yellow and grey eggs was 1132.7 ± 484.1,766.4 ± 524.3 and 745.5 ± 487.2, respectively, a decrease of 32.3% when orange eggs became yellow and 34.3% when they turned grey. This decrease was probably due to unfertilized eggs dropping off and some eggs being eaten by the brooders during the incubation period.
Egg numbers/g egg weight were found to be 11360.1 ± 1642.1,10715.7 ± 2725.3 and 8634.0 ± 1892.3 for orange, yellow and grey eggs, respectively. When compared to orange eggs, yellow eggs were slightly heavier (6%), but grey eggs were significantly heavier by 31.6%. The increase in the weight of the grey eggs can be explained by the elongation of fully formed organs and appendages by about 17 days post fertilization.     

Optimization of stocking density of freshwater prawn Macrobrachium rosenbergii (de Man) in carp polyculture in Bangladesh

A study was conducted to optimize stocking density of freshwater prawn, Macrobrachium rosenbergii, in carp polyculture for 3 months in 10 experimental ponds of 80 m². Five stocking densities of prawn, 2500, 5000, 7500, 10 000 and 12 500 ha^?1, were assigned to treatments T₁, T₂, T₃, T₄ and T₅ respectively. The densities of catla, Catla catla, rohu, Labeo rohita and silver carp, Hypophthalmicthys molitrix, were 2500, 5000, and 2500 ha^?1, respectively, in each treatment. Each treatment had two replicate ponds. The mean initial weights of prawn, catla, rohu and silver carp were 1.1±0.02, 8.28±0.1, 25.2±1.1 and 36.32±1.2 g respectively. A pelleted diet containing 30% protein was prepared using fish meal, meat and bone meal, mustard oilcake, rice bran, wheat bran and molasses, and was fed twice daily at a rate of 5% of fish biomass. Water quality parameters were measured fortnightly and the ranges of temperature, pH and dissolved oxygen were 27.5–1.3°C, 6.9–8.6 and 4.5–8.6 mg L^?1 respectively. Feed conversion ratios ranged from 2.05 to 2.20 among the treatments. Per cent survival (%) of prawns ranged from 72% to 78%, while it varied from 80% to 93%, 90% to 95% and 90% to 92% for catla, rohu and silver carp respectively. The results showed that there were no significant differences among the weight gains of prawn and carp in different treatments. However, the overall total production of prawn and fish together was significantly (P<0.05) higher in T₃ and T₄ compared with other treatments. The total production for 3 months ranged between 2618 and 2916 kg ha^?1. The production of prawn was significantly higher (361.3 kg ha^?1) in T₅ with a highest stocking density of 12 500 prawn ha^?1. Although there was no significant difference (P>0.05) between the total production of prawn and fish together in T₃ and T₄, the highest net profit (Tk. 69 006 ha^?1) was obtained in T₄. Therefore, from the result of the study it may be concluded that a stocking ratio of 4:1:2:1 of prawn:catla:rohu:silver carp at a total density of 20 000 ha^?1 may be recommended for prawn–carp polyculture in ponds.     

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.     

Chitosan as a wall material for a microencapsulated delivery system for Macrobrachium rosenbergii (de Man) larvae

Chitosan has been widely accepted as a wall material for preparing microcapsules of various purposes in human medicine. The possibility of using chitosan as a wall material for microencapsulating nutrients and drugs for aquaculture purposes, specifically to Macrobrachium rosenbergii larvae was evaluated in this study. Two types of chitosan-coated microcapsules were prepared using either acetone (MEC-A) or NaOH (MEC-N) as the cross-linking agents. They were compared with a microbound diet relative to total leaching of nutrients and free amino acids (FAA). Among the microcapsules, MEC-N showed the lowest level of total leaching of nutrients (23.3%) during 5 h of immersion in seawater and released 65% FAA after 60 min. During laboratory trials, 75% larvae had accepted the MEC-N capsule. The results of the study suggest that chitosan can be used as a wall material for preparing microcapsules to deliver drugs and nutrients to M. rosenbergii larvae.     

Effect of feeding Lactobacillus-based probiotics on the gut microflora, growth and survival of postlarvae of Macrobrachium rosenbergii (de Man)

The present study was conducted to study probiotics treatment in the post‐larval diet of Macrobrachium rosenbergii. Three hundred postlarvae (average weight, 114–118 mg±0.11) were divided in five experimental groups each with four replicates. The experiment was conducted for 60 days. Experimental diets were identical in all the aspects except for variation in the probiotics strain. T1 and T2 groups were fed Lactobacillus acidophilus (140×10¹¹ CFU 100 g^?1) and L. sporogenes (24×10⁷ CFU 100 g^?1) respectively. The T3 group was fed L. sporogenes bioencapsulated in Artemia nauplii. T4 was the control group (without probiotic) whereas T5 was fed Artemia along with control diet. The bacteriological study indicated that the gut microflora of postlarvae are devoid of lactic acid bacteria. The probiotic strains were found to have inhibitory effects against the gram‐negative bacterial flora present in the gut. Growth of the probiotic fed groups was significantly higher (P<0.05) than the control group. Significantly higher growth (P<0.05), per cent weight gain (132.5%), specific growth rate (1.41%), feed efficiency ratio (FER) (0.45), protein efficiency ratio (1.29) and protein gain (161.6%) were recorded in T3 group fed Artemia bioencapsulated L. sporogenes over the control group (P<0.05). Although insignificant (P>0.05), growth‐promoting effects of L. sporogenes were found to be higher than L. acidophillus. Survival of the postlarvae was not affected by probiotics in the diet.     

Probiotic effect of Bacillus NL110 and Vibrio NE17 on the survival,growth performance and immune response of Macrobrachium rosenbergii (de Man)

Eight hundred and eighty‐five strains of bacterial isolates from various samples associated with the natural habitat of Macrobrachium rosenbergii were screened for their probiotic potential. Two putative probionts namely Bacillus NL110 and Vibrio NE17 isolated from the larvae and egg samples, respectively, were selected for experimental studies and were introduced to the juveniles of M. rosenbergii (0.080±0.001 g) through different modes such as through feed, water and both. The probiotic potential of the above bacteria in terms of improvements in water quality, growth, survival, specific growth rate (SGR), feed conversion ratio and immune parameters was evaluated. The treatment groups showed a significant improvement in SGR and weight gain (P<0.001). Survival among different treatment groups was better than that in the control group. There were also significant improvements in the water quality parameters such as the concentration of nitrate and ammonia in the treatment groups (P<0.05). Improvements in immune parameters such as the total haemocyte count (P<0.05), phenoloxidase activity and respiratory burst were also significant (P<0.001). It is concluded that screening of the natural microflora of cultured fish and shellfish for putative probionts might yield probiotic strains of bacteria that could be utilized for an environment‐friendly and organic mode of aquaculture.     

Interactions of different sodium and potassium concentrations on Macrobrachium rosenbergii (de Man) offspring quality parameters

The present study evaluated various sodium and potassium concentrations in hatchery water to determine which proportions would be optimal for Macrobrachium rosenbergii larviculture. Using a closed RAS system (60‐L), experiments were conducted in two stages. In the first stage, larval quality parameters were compared among triplicate treatments of sodium (2000, 3000, 4000 and 5000 mg L^?1) and potassium (100, 150, 200 and 250 mg L^?1). During the second stage, these same parameters were compared from interactions of the two best concentrations determined in the first stage. Initial larval density was fixed at 100 larvae L^?1 and larval quality parameters such as larval stage index (LSI), larval condition index (LCI), larvae dry weight, survival (%), LC₅₀‐24 h for formalin stress and time of the first postlarvae (PL) appearance were measured. Results showed that during the early larval period time LSI, LCI and survival parameters were affected only by potassium and the interaction with sodium was not significant. At a later period of the larval development, interactions between both sodium and potassium were measurable for LSI (P < 0.05) while the interactions on LCI and survival were not significant. Measurable differences among the combined treatments 4000 mg L^?1 sodium and 150 mg L^?1 potassium resulted in the best performance for M. rosenbergii larviculture. This concentration also provided the highest final survival to PL metamorphosis (40.6 ± 2.5%) which was at least 10% higher than the other treatments.     

Observations on salinity tolerance and osmoregulation in laboratory-reared Macrobrachium rosenbergii post-larvae (Crustacea: Caridea)

The tolerance of postlarval Macrobrachium rosenbergii to gradual and rapid increases in salinity was determined. Mortalities occurred at salinities around 25‰ and increased rapidly at levels ≥30‰ in both cases. However, acclimation substantially increased survival time at 35‰.Freezing point depressions of blood were measured from laboratory-reared M. rosenbergii postlarvae and juveniles exposed to various salinities from fresh water to approximately 35‰. The blood concentration was hyperosmotic to the medium at salinities from fresh water to about 17–18‰ and hypoosmotic at higher salinities. Postlarvae maintained a nearly constant blood concentration (freezing point depression = ?0.89 ± 0.13°C) over a wide range of external salinities (fresh water to about 27–30‰). The animals' osmoregulatory mechanisms failed at salinities ≥30‰, and thereafter the blood concentration paralleled that of the medium. The blood concentrations of juvenile shrimp grown for 5 months at salinities from fresh water to about 15‰ (freezing point depression = ?0.88 ± 0.07°C) closely resembled those of postlarvae.The osmoregulatory performance of young M. rosenbergii is generally similar to that of other brackishwater animals, but in their ability to hyperosmoregulate effectively in fresh water they more closely resemble fresh water species. It is suggested that M. rosenbergii may be able to conserve salt in dilute media by producing blood-hypoosmotic urine.An interesting stress symptom often preceded death of postlarvae in high salinities. The animals changed gradually from nearly transparent to opaque white and then died, usually within a day or so.     

Effects of Moina micrura (Kurz) from two different culture sources as a replacement of Artemia spp. in production of Macrobrachium rosenbergii (de Man) post-larvae

Abstract. The effects of Artemia spp. and of Moina micrura from two culture sources, poultry manure and Chlorella supplemented with baker's yeast, on production of Macrobrachium rosenbergii (de Man) post-larvae (PL) were evaluated. Significantly higher production of 18·13 ± 1·45 PL/I was obtained for the larvae fed with 50:50 mixture of Artemia and Moina cultured on poultry manure compared to that for larvae fed Artemia alone (14·27 ± 1·64PL/I). Regardless of the culture source, the post-larval production was the lowest (9·23 ± 1·22 and 11·26 ± 1·33 PL/I for the larvae fed Moina. The higher dietary value of Moina cultured on poultry manure was related to the high content of n–3 HUFA particularly 20:5n-3 compared to Artemia and Moina cultured on Chlorella and yeast.     

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.     

Long-term cryopreservation of spermatophore of the giant freshwater prawn, Macrobrachium rosenbergii (de Man)

Long‐term cryopreservation of the giant freshwater prawn, Macrobrachium rosenbergii, spermatophores using glycerol (Gly) and ethylene glycol (EG) as cryoprotective agents (CPAs) was studied. The tolerance of sperm to cryopreservation was evaluated on the basis of sperm survival and fertilizing ability. The survival of the sperm was determined by trypan blue staining, while the fertilizing ability was assessed from artificial insemination of the cryopreserved spermatophores. The rates of embryo survival on day 5 after spawning and of spermatophores capable of producing embryos survived to hatching were determined. Storage of spermatophores at ?20°C without CPA for a short period of up of 1–5 days decreased the sperm survival significantly and did not preserve fertilizing ability. Preservation at ?20°C in the presence of 10% or 20% Gly or of 10% or 20% EG offered a simple and efficient short‐term storage up to 10 days. For a long‐term storage, cryopreservation in the presence of 20% EG at ?196°C was more efficient than at ?20°C. High sperm survival rates and high fertilizing ability were recorded from those cryopreserved at ?196°C for up to 150 days. High sperm survival rates with moderate levels of fertilizing ability were obtained from those cryopreserved at ?20°C for not more than 30 days. The results indicate that preservation at ?196°C with 20% EG is a suitable procedure for long‐term storage of the giant freshwater prawn spermatophores.     

Bacterial microflora associated with farmed freshwater prawn Macrobrachium rosenbergii (de Man) and the aquaculture environment

The initial counts of bacteria associated with farmed giant freshwater prawn (Macrobrachium rosenbergii de Man) as well as with the water and sediment from two farms located at Kottayam district in Kerala (India) were determined. A total of 367 randomly selected isolates were characterized and identified. Prawn samples yielded mean microbiological counts of 4.92 log CFU g^?1 of shell with muscle and 7.78 log CFU g^?1 of intestine at 30°C. Bacterial numbers in the intestine of prawn were much higher than those in the pond water. Motile and non‐motile aerobic Gram‐negative bacteria together with Enterobacteriaceae accounted for 60–70% of the mesophiles isolated from water and prawn. However, the microorganisms isolated in significant numbers from shell with muscle and intestine of prawn were not recovered from the growing waters. Among Gram‐positive bacteria, Micrococcus, Bacillus, coryneforms, and Arthrobacter were found. Faecal coliforms and enterococci were found in significant numbers in M. rosenbergii. The rearing practices such as feeding and pond fertilization could have influenced the microflora in prawn. The commensal microflora of freshwater prawn included opportunistic pathogens such as Aeromonas spp. and Streptococcus spp. Storage of prawn at elevated temperatures can permit their survival and growth leading to quality loss. Care should be exercised during handling and processing to prevent contamination of edible meat.     

Over-wintering growth of Macrobrachium rosenbergii (de Man) with carp polyculture in Bangladesh fed formulated diets

An experiment was conducted from December 2003 to April 2004 to observe the over‐wintering growth of freshwater prawn, Macrobrachium rosenbergii, with catla, Catla catla and rohu, Labeo rohita in polyculture using formulated diets. The study was conducted in eight experimental ponds, each 80 m². Three experimental diets containing 30% protein were prepared using fish meal, meat and bone meal, mustard oilcake, rice bran, wheat bran and molasses (binder), and assigned to treatments T₁, T₂ and T₃ respectively. A commercial diet from Saudi‐Bangla Fish Feed was assigned to T₄ (reference diet). Each treatment had two replicate ponds. Juvenile prawns and catla and rohu fingerlings (initial weight 1.60±0.10, 30.0±1.2 and 25.0±1.1 g respectively) were stocked at a ratio of 2:1:1 (prawn:catla:rohu). A total of 160 prawn and fish (20 000 ha^?1) were stocked in each pond. Fish were fed twice daily at 3% body weight (b.w.) for the first 3 months and 5% b.w. for the last 2 months. Prawns in T₁ fed diet 1 had significantly higher (P<0.05) weight gain compared with that of T₃. The reference group and T₂ had intermediate values not significantly different from either. Weight gains of catla and rohu were significantly higher in T₁. The feed conversion ratio values of different diets ranged between 1.89 and 2.13. Survival (%) ranged from 90.0% to 95.0% for catla, 87.5% to 92.5% for rohu and 70.0% to 76.3% for M. rosenbergii, and there were no significant differences (P>0.05) among different treatments. Total production ranged between 2196 and 2679 kg ha^?1, with T₁ showing significantly higher production and net profit (taka 56 531.9 ha^?1). The results of the study demonstrated that it is possible to culture M. rosenbergii with carp in polyculture during the winter utilizing the late‐produced PLs. Further study is needed to determine the optimum stocking density of M. rosenbergii in carp polyculture.     

Yield characteristics and morphometric relationships of giant freshwater prawn,Macrobrachium rosenbergii (de Man, 1879)

Meat yield of 233 individuals of giant freshwater prawn, Macrobrachium rosenbergii (de Man, 1879), and their morphometric relationships were examined. Morphometric parameters of different length and weight measurements were recorded for both the sexes separately and subjected to analysis. The meat yield of prawns was size and sex dependent with females showing significantly greater (P < 0.05) tail meat yield than males. The tail meat as a body weight percentage ranges from 26.12 to 40.75 and 32.97 to 42.11 in males and females, respectively. Much of the differences in yield are related to the size and weight of the head and claws. The head weight of males was observed to be higher compared to females in all the size classes. Regression slopes of total length versus body weight and total length versus head weight were significantly higher than critical isometric value indicating high positive allometric growth in both the sexes, with males showing significantly higher (P < 0.05) slope than females. The relationship parameters of total length versus tail weight and total length versus tail meat showed a positive allometric growth in females, whereas it is isometry and negative allometry in males. The morphometric relationship of tail length versus all weight measurements showed positive allometry and negative allometry in females and males, respectively.     

POPULATION PROFILE DEVELOPMENT AND MORPHOTYPIC DIFFERENTIATION IN THE GIANT FRESHWATER PRAWN Macrobrachium rosenbergii (de Man)

Post-larval populations of Macrobrachium rosenbergii are characterized by a homogenous size distribution curve which changes, with time, to a positively skewed curve, with some individuals demonstrating a higher growth rate than the rest of the population. No morphotypic variation is observed at the post-larval and juvenile stages, and the ratio of males to females is 1:1, equally distributed along the whole size distribution curve. Both the mean weight and the development of the skewed distribution curve are inversely affected by increasing density. In a mature population, three male morphotypes can be clearly differentiated by claw color, relative size within the population and the ratio of claw length to body length. The Small Male (SM) morphotype is characterized by short clear claws, while the two larger morphotypes are characterized by Orange Claws (OC) and Blue Claws (BC). Their relative occurrence in the population is SM 20–25%, OC 15–25%, and BC 5–10%. No apparent morphotypic variation exists in females and their size distribution is generally homogenous. Increased population density does not change the relative position, nor the relative proportions of the three male morphotypes and the females, however, the degree of skewness of the curve is inversely related to the density.