Freshwater prawn farming is expanding fast all over the world and therefore
concerted efforts are being made to increase the seed production (Soundarapandian,
2008). More Macrobrachium rosenbergii is found extensively in the
tropical and subtropical fresh waters of India, Seri Lanka, Thailand, Malaysia,
Philippines. It is generally found in freshwater, in ponds, rivers, lakes, ditches,
canals, depressions, low-lying floodplains and river mouths. Most of the species
spend their early life in brackish water that is connected directly or indirectly
with the sea. Some species complete their life cycles in freshwater but these
are not of commercial importance. Macrobrachium rosenbergii is most suitable
for culture due to its large size and its less aggressive nature under culture
conditions. There are 150 species of Macrobrachium in the world, of which
49 are commercial. Twenty-seven of the commercial species are found in Asia
and the Pacific. Most live in freshwater. Tayamen (2001)
of which about 25 species are found in India (Soundarapandian
and Kannan, 2008).
The farming of the giant freshwater prawn Macrobrachium rosenbergii
popularly known as 'scampi' has been expanding in India recent years (Mitra
et al., 2005). The freshwater prawns (Macrobrachium rosenbergii)
have been the focus of research in India because of the success achieved in
its commercial farming in southern states (Jain et al.,
India with its aquaculture production of 3.12 million tones is placed second
only after China in the year 2006 (FAO, 2009). Freshwater
crustaceans including prawns though produced in meager quantities (around 953
198 tones) have gained significance as high value commodity by standing as fifth
highest valued species group. Farming of giant freshwater prawn Macrobrachuim
rosenbergii popularly known as scampi is spreading fast to all Indian states
due to its large size attainment, tolerance to water quality changes, ability
to cope with handling stress and ability to feed on unconventional feeds (Yathavamoorthi
et al., 2010).
The global annual production of freshwater prawns (excluding crayfish and crabs)
in 2003 was about 280,000 tons, of which China produced some 180,000 tons, followed
by India and Thailand with some 35,000 tons each. Additionally, China produced
about 370,000 tons of Chinese river crab (FAO, 2003).
The prawn is one of the high value aquaculture products emerging from Asia.
At present feed is the largest single cost item, as it constitutes 40-60% of
operational cost in prawn production.
Water quality influences the level of growth that can be achieved with freshwater prawns. Dissolved oxygen is particularly important and a good oxygen-monitoring program is necessary because prawns live on the bottom, levels of dissolved oxygen should be routinely monitored within the bottom 0.3 m (1 ft) depth of water. Oxygen levels at the surface can potentially be lower than those at the bottom (MSUC Cares/CommercialPrawnProduction).
A high pH can cause mortality either directly by means of creating a pH imbalance
relative to the prawn tissue or indirectly by causing a larger proportion of
ammonia to exist in the toxic un-ionized form (Costa-Pierce
et al., 1984).
Water temperature is probably the most important environmental variables in
prawn cultures, because it directly affects metabolism, oxygen consumption,
growth, molting and survival (Soundarapandian et al.,
2008). Macrobrachium rosenbergii do best in water of 26 to 30 degrees
C. (79 to 86 F). They can survive from 22 to 32 degrees C. (71 to 90 degrees
F.) but growth and activity becomes at best sluggish at the ends of their range
(Costa-Pierce et al., 1984).
MATERIALS AND METHODS
Experimental conditions: The experiment has started on the first of August 2009.The study was carried out in laboratory aquariums to find out Macrobrachium rosenbergii food habits and its survival and growth with different food items which are easily available. The rearing of Macrobrachium rosenbergii was done in 5 aquariums (each of 60x40x30 cm size) were filled with water and were continuously aerated by means of an electric compressor. Polyvinyl Chloride (PVC) tubes and some stones were put on the bottom of each aquarium as sheltering place for Rosenbergii juveniles.
Feeds and feeding rate: Feeding content was adjusted based on daily observations of feed intake of the rosenbergii juveniles. Total feed rotation was divided into two parts; about 1/3 of the total feed was given at 10 a.m. and the remaining amount at 10 p.m. At the end of the experiment, all rosenbergii (in bulk) from each tub were weighed. Five different types of feed with change in their composition were tested. There were 5 dietary treatments. Ingredient compositions of the test diets were similar as in Table 1.
Sample collection: Prawns were measured for weight every fifteen days and water sample collection for analyzing of physic-chemical were carried at 10 a.m and usually from 5-10 cm depth from the water surface, once a week for pH and Do and every day for temperature.
|| Composition of test diets
Growth measurements: Body weights (g), of prawns were measured biweekly and Weight Gain (WG) %, Specific Growth Rate (SGR), Normalized Biomass Index (NBI), as follow:
Water quality parameters: Temperature, pH, dissolved oxygen were measured
using Standards Methods for the Examination of Water and Waste Water (APHA,
AWWA and WPCF, 1995).
Statistical analysis: Data were statistically processed for one analysis
of variance (ANOVA) with Duncans Multiple Range Test (DMRT) according
to Snedecor and Cochran (1961). To find out the significant
differences among the treatment groups for growth studies at different comparison
of test diets.
Growth of prawn analysis: Growth parameters of M. rosenbergii in relation to different composition of test diets are shown in Table 2. During the period of the study conducted using different feeds in M. rosenbergii showed significantly greater growth in terms of Weight Gain % (34.6 g), specific growth rate (2.04) and improving in normalized biomass index (3.99) were observed at the diet III including protein 45% during 6 month. While the minimum WG , SGR and NBI, measured for the Rosenbergii fed treatment -V containing 75% dietary protein and showed lowest significantly values until the end of experiment.
Analysis of feeding experiments carried out with the weight gain of freshwater
prawn Macrobrachium rosenbergii in order to determine the requirement
of different dietary supplements on growth rate of Macrobrachium rosenbergii
especially in term of survival rate is shown in Table 3.
|| Growth parameters of the freshwater prawn fed different composition
at the end of 6 months
Survival rate performance of the freshwater prawn fed
different composition at the end of 6 months
||Fluctuation in (Mean±SD) pH of water samples at during
|**Fluctuation in (Mean±SD) pH of water by the different
diet are not significantly different
|| Fluctuation in (Mean±SD) DO of water samples at during
This shows significantly higher survival rate (40) was measured for the rosenbergii
fed treatment -III with 45% dietary protein and survival rate obtained for the
prawns fed with diet II was 36.66 and this tank had higher survival rate than
tank No. 1 with the prawns fed with diet I and tank No. 4 with the prawns fed
with diet IV ( 26.66 and 20 ). While the minimum survival rate was measured
for the rosenbergii fed treatment-V with 75% dietary protein showed significantly
lowest survival rate (13.33).
Physico-chemical analysis parameters of water: Fluctuation the means values±SD of water sample quality parameters such as like pH, Temperature, DO in the investigation period that are important water quality parameters in grow M. rosenbergii juveniles have been depicted in Table 4 and 5.
The fluctuations in the values of pH in relation to different composition of test diets are represented in Table 4. According to Table 4, the maximum value of pH (8.38±0.026) was recorded for the fed treatment-I on the August month and the minimum pH value (7.4±0.17) was for diet-V on the January.
The Fluctuation in the level of Dissolved Oxygen (DO) for each treatment are represented in Table 5. The maximum concentration of Dissolved Oxygen (DO) was 7±0.17 mg L-1 recorded for Diet-II and minimum obtained value (5±0.21 mg L-1) was recorded for fed treatment-III.
Generally all the parameters quality were optimum for the growth of the prawn and were within the acceptable range for freshwater prawn, Macrobrachium rosenbergii.
The study carried out with the feeding experiments showed that the giant freshwater
Macrobrachium rosenbergii require dietary protein for weight gain, specific
growth rate and survival rate Gomez et al. (1988).
Studied on the effect of dietary Protein and energy level on growth of the giant
freshwater Macrobrachium rosenbergii and they have concluded that the
dietary energy levels improved growth and feed efficiency.
This study brought out that fresh water prawn required dietary supplements
with protein level ranging from 30-45% and best growth was seen in these protein
level tank II, III and confirmed the best result in terms of growth weight gain
%- specific rate growth and survival rate. However Habashy
(2009) studied on the growth of juvenile freshwater prawn, Macrobrachium
rosenbergii, he had concluded that freshwater prawn required dietary protein
level ranged from 25-35%.
In the present study the highest weight gain (30.99, 34.60), survival rate
(36.66, 40) and specific growth rate (1.91, 2.04) were recorded in aquarium
number fed with diet II and III including 30 and 45% dietary protein level but
Habashy (2009) has given the protein requirement for
the best prawns growth ranged from 25-35%. Weight gain and feed efficiency increased
as the energy level increased.
This study showed increasing the dietary protein levels does not improve growth.
Protein levels tested in this study did not affect the growth terms in range
60-75% but Gomez et al. (1988) have told increasing
the dietary energy level improved growth and feed efficiency.
The results of the present study showed that the 45% protein diet was recommended
to achieve the optimum growth rate of freshwater M. rosenbergii but a
study by Chowdhury et al. (2008) has shown that
35% protein diet shows the optimum growth indices of freshwater prawn M.
Based on this study the suitability of the used feed ingredients could be clarified. Thus the present study indicated that the prawns fed with diet III (45% protein) displayed highest growth measurements While the minimum gain terms were measured for the fed treatment V with 75% dietary protein. In summary, the results suggest that the most suitable diet in supplemented feed for rearing M. rosenbergii should be supplements with protein level ranged from 30-45%.
I wish to express my sincere appreciation to Dr. Kranti Yardi, my guide. This investigation was completed with her valuable guidance. I would like to express my gratitude to my family especially my parents for their encouragement and valuable help they have always been unflinching, supporting me in all my way to achieve my goals.