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HIGH DENSITY CULTURE OF
WHITE SHRIMP, Litopenaeus vannamei,
By
Liaw Kok Eng, Yu Kar Fook* and
Angelito O. Abaoag |
ABSTRACT The culture of white shrimp, Litopenaeus vannamei, increased several folds during the past 5 years after the tiger prawn culture, Penaeus monodon, was discontinued due to widespread disease. White shrimp cultures are perceived to be better than tiger prawn due to its relative ease of growing (less than 4 months), higher density and resistance to disease. This study deals with the effect of probiotic treatment in pond bottom soil and water column and the enrichment of shrimp feeds. Results shows that thru this 3-prong treatment approach, density can be increased 200%, mortality reduced by 80% and overall yield increased by 462.5%. The Bionovar 3-prong treatment involves the treatment of the pond bottom soil during preparation and during the grow-out phase to prevent the build-up of the sludge in th middle of the pond bottom. Water column treatment and feed enrichment ensures good water quality and digestibility and adsorption of the nutrients. |
INTRODUCTION The white shrimp culture industry has been touted as the alternative to tiger prawn culture but most farms are now being hit by disease and low productivity in the last few years. Farms in the region are being abandoned or activity drastically reduced due to sustain losses incurred by farmers. This scenario will persist due to the continuous environmental degradation throughout the coastal regions anywhere in the world. Bionovar International has focused its research effort in the development of a system solution to arrest and rejuvenate the industry thru application of microbial formulations, complimenting it with protocols and standards. This paper presents the field trial conducted by Bionovar International on white shrimp cultures which was conducted from 2004 to 2005. |
MATERIALS AND METHODSMicrobial Products Development. Bionovar International Pte Ltd (BIPL) developed several microbial products that are applicable for white shrimp (Litopenaeus vannamei) cultures. Laboratory and bench-scale tests shows that two of BIPL products can be used in the treatment of pond bottom soil and pond water, BioSOIL and BioGREEN, respectively. Another product, BioGROW, is shown to exhibit enzymatic activity for the improvement of the digestibility of feeds. The three product for prawn/shrimp cultures were complimented with protocols for application and culture management. The system that was derived was termed, BioSEA or Bionovar Sustainable Enhanced Aquaculture. Field Trial – White Shrimp. The BIPL products was tested in actual ponds located in Sitiawan, Perak, Malaysia. Two 1,000 square meter ponds with an average depth of 1.2 meters were used to test the product to rear white shrimp. Concurrently, similar ponds owned and managed by local farmers were used as control for the comparison. |
Table 1. Comparative
pond preparation and management of normally cultured tiger prawn/white
shrimp as compared to BioSEA system |
|
Normal Cultures |
BioSEA Cultures |
Pond Preparation |
1. Drying of ponds before every cropping. 2. Application of tea seed to kill predators. 3. Application of lime, calcium carbonate or calcium hydroxide to neutralize acidity. 4. Application of chemical fertilizers or manure to enhance growth of algae |
1.Drying of ponds once every 2 – 3 cropping. 2.Application of tea seed to kill predators. 3.Application of compost as food to enhance growth of algae. 4. Application of inocula.
|
Pond Fertilization |
1.Fertilization during grow-out period is done thru addition of chemical fertilizers or raw chicken manure. 2. Fertilization dosage depends on “perceived” algae bloom and no fix amount. |
1. Fertilization by addition of compost and BioGREEN at regular interval. |
Pond Maintenance |
1.Water change from the reservoir has no definite timeframe and interval. 2.Water change rate is dependent on water quality. 3.Rate can vary from 30 to 50% of volume. 4. Chemicals such as chlorine, gasoline, copper sulfate and aluminum compounds are used to suppress algal bloom and to “disinfect” from viruses. |
1. Water change of equal to or less than 10% on a regular basis. |
Post Harvest |
1.Draining of water to river or sea. 2. Removal of sediments to aerate and degrade. |
1.Draining of water to wastewater reservoir for treatment and recycling. 2. Treatment of sediments on site.
|
Fertilization and Inocula Application. Fertilizer (compost) application is done every 15 days from DOC 1 to 60 and every 10 days from DOC 61 to harvest. Inocula applications follow the schedule below: BioGREEN - For white shrimp with density of 300 per m2, application of 0.2 g per m2 per week for first 60 days, 0.2 g per m2 per 5 days for DOC 61 to 90 and 0.2 g per m2 per 3 days from DOC 91 to harvest. BioSOIL - For white shrimp with density of 300 fry per m2, application of 0.1 g per m2 per week for first 60 days; 0.2 g per m2 per week from DOC 61 to 90 and 0.2 g per m2 per 5 days from DOC 91 to harvest. BIOGREEN and BIOSOIL are mixed with starch and calcium carbonate at the ratio of 1:1:2 (inocula:starch:calcium carbonate). BioGROW – Addition of 1.0 kg per 1,000 kg of commercially available feeds at the nutrient level of 38 – 42% crude protein and 2 – 3% crude fat. |
Water Monitoring. Water monitoring was done regularly from the day of seeding to the day of harvest. Temperature, pH and dissolved oxygen levels were taken twice a day, one early morning and one late afternoon. Ammonia and nitrate are monitored once a week from DOC 1 to 45, once every 5 days from DOC 45 to 60, once every 3 days from DOC 61 to 75 and once a day from DOC 76 till harvest. Phosphorus and alkalinity are measured once every week from DOC 1 till harvest. Fry Sampling. Fry sampling are done regularly from day 30 until harvest. Nets are cast every 10 days from DOC 30 to 60 and every 5 days from DOC 60 till harvest. In each sampling, the average of 5 cast nets were done. Shrimps were counted and weighed before segregated into sizes. Days of Culture and Harvest. White shrimp was harvested at day 90 to 100 for both normal and BioSEA treated.. Data Collection and Analysis. Analysis of variance was used to compare the effects of the BioSEA inoculants on the water parameters, and growth and yield of prawn/snrimps. Correlation of the different physico-chemical parameters was also done. |
Figure 1. Harvesting of White Shrimps
RESULTS AND
DISCUSSION |
Table 2. Overall means
of water quality variables in
tiger prawn and white shrimp |
Parameters |
White Shrimp Ponds |
|
Normal Cultivation 2 |
BioSEA 2 | |
Temperature, oC | 28.49 + 0.16 a | 28.60 + 0.16 a |
Dissolved Oxygen (mg/L) | 4.26 + 0.21 a | 6.11 + 0.21 b |
Ionized Ammonia (ppm) | 1.500 + 0.189 a | 0.960 + 0.168 a |
Reactive Phosphorus (ppm) | 0.359 + 0.045 a | 0.342 + 0.044 a |
pH | 8.15 + 0.09 a | 7.14 + 0.09 b |
Alkalinity (ppm as CaCO3) |
151.86 + 4.58 a | 147.98 + 4.36 a |
Fig
2. Average body weight of white shrimp of normal cultivation (WS-N) and
|
|
Water parameters of BioSEA treated ponds shows improvement in quality as compared to normally cultivated ponds. The average body weight of white shrimps are significantly higher than normally cultured shrimp from DOC 50 until harvest. |
Table
3. Comparative density, mortality and yield of
white shrimp culture in Sitiawan, Malaysia |
Normal Culture | BioSEA treated | |
Density (fry/m2) | 100 | 300 |
Pond size, m2 | 1,000 | 1,000 |
Total fry population | 100,000 | 300,000 |
Days of Culture till harvest | 120 | 120 |
Average Body Weight, g | 12.13 | 13.21 |
Yield, in kg (at 100% survival) | 1,213 | 3,963 |
Actual survival rate, % | 50 | 90 |
Actual yield, kg | 606.50 | 3,566.70 |
Table 4. Comparative
feed conversion ratio of normal cultures of
tiger prawn/white shrimp as compared to BioSEA treated tiger prawn/white
shrimp |
Parameters | White Shrimp | |
Normal Culture | BioSEA Treated | |
Yield, kg | 606.50 | 3,566.70 |
Total Feed Consumption, kg | 1,150.00 | 5,425.00 |
Feed Conversion Ratio | 1.89 | 1.52 |
Fig 3. Five gram fry at DOC 60, density 300 fry/m2 and treated with BioSEA. |
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