Endhay K. Kontara
Brackishwater Aquaculture Development Centre
In the Southeast Asia region, shrimp farming has attracted considerable attention not only as a source of food supply but also as foreign exchange earner. Of the species found in the area, tiger shrimp or Penaeus monodon is the most widely cultivated in brackishwater ponds. The ASEAN countries, realizing the benefit from the industry, decided to give shrimp farming high priority in their fisheries programme.
Prior to artificial hatching of P. monodon, fishfarmers follow the traditional method of shrimp culture. The practice is characterized by low production, 100–300 kg/ha/yr; irregular pond size and shape; and relatively low production inputs. There is also no supplementary feeding given and water management is by tidal fluctuation. No definite stocking density is used but seeds grown to market size comes with the tide during pond watering.
Today, with the availability of hatchery-produced seedlings and the improved management techniques developed such as: application of lime prior to stocking to condition the soil; use of pesticide to control or eradicate pests and predators; application of organic and inorganic fertilizers to enhance natural food production; increase water depth and stocking density, shrimp production have increased appreciably over the years. Under simple extensive method, production is increased from 400–800 kg/ha/yr; semi-intensive operations, 800-1 600 kg/ ha/yr; and 5 000–16 000 kg/ha/yr under intensive culture practices.
The following discussion presents the physico-chemical parameters that affect shrimp culture operations irrespective of the type of production methods applied.
2. WATER QUALITY
The first and foremost important consideration in shrimp cultivation is the water quality. Water quality should be conducive to good growth of the shrimp. Some of the essential qualities of pond water includes temperature, salinity, dissolved oxygen, pH, nitrogen, phosphorous and potassium which enhance the growth of algae which serve as food. Hydrogen sulfide also affects the growth of shrimps.
Temperature affects the growth and survival of shrimps. The rate of growth increases with temperature, however, higher temperature causes mortality. Temperatures between 26°C to 30°C are considered best in terms of maximum production. Temperature above 32°C should be cause of concern. High temperature can be avoided by deepening of ponds, water exchange and aeration.
Young shrimps can tolerate wide range of salinity. However, very little is known of the salinity tolerance of sub-adult and adult shrimp. It is observed that P. monodon and most Metapenaeus spp. can grow in almost freshwater. Penaeus merguiensis and P. indicus require more saline water, above 10 ppt. Piyakarnchana, et. al. (1975) reported that optimal growth of P. merguiensis was obtained at 27 ppt but that growth was good within the range from 20 to 30 ppt.
2.3 Dissolved oxygen
Maintenance of adequate levels of dissolved oxygen in the pond water is very important for the shrimp. It was observed that when dissolved oxygen reaches 3 ppm or below in fishponds, remedial measure is necessary. Shrimps are quite sensitive to low oxygen levels. With little information available, we can perhaps state that growth is best at dissolved oxygen level above 3 ppm. Shigueno (1975) recorded a die-off in a pond when oxygen level reached 2.7 ppm during the night. Mortality can be reduced in shrimp suffering from a lack of dissolved oxygen if the oxygen level is raised quickly. Oxygenation of pond water is provided by the use of aeration devices such as paddlewheels where water supply is within easy reach and control, frequent water exchange should be made particularly during high temperatures. Aeration devices during early mornings would help prevent low oxygen levels that have occurred at night time.
2.4 Water pH
Another important aspect in shrimp culture is the water pH. Low water pH affect the shrimp directly. Wickins (1976) found that even though P. monodon grow without suffering mortalities with water pH of 6.4 in the presence of inorganic carbon, growth was reduced to 60 percent. In water with pH of 6.4 and less than 10 to 12 mg/l of inorganic carbon, P. merguiensis and P. aztecus exhibited greatly reduced growth and lower survival. When pH fell below 5.0, heavy mortalities occurred. A fall in pH have indirect effect, for instance, resistance of the shrimp to pathogens might be reduced. Desirable pH is above 7 to 8.5.
2.5 Nitrogen compounds
Wickins (1976) discussed the three forms of nitrogen compounds and the effects of sub-lethal levels on shrimp growth. Two tests with nitrate showed that the growth of P. monodon was not affected by a concentration of 200 mg/l NO3 after five weeks of exposure. In a test with P. indicus, growth was reduced by nearly 50 percent over a period of 34 days where nitrate concentration was 6.4 mg/l NO2. For ammonia, chronic toxicity test with five species of penaeid shrimps, P. japonicus, P. occidentalis, P. schmitti, P. semisulcatus and P. setiferus, showed that a mean concentration of 0.45 mg/l NH3 reduced growth by 50 percent of the control. Wickins estimated that a “maximum acceptable level” at which growth would be reduced by only 1 to 2 percent is 0.10 mg/l NH3.
There are three forms of nitrogen namely; nitrate, nitrite and ammonia. The concentration range of these nitrogen compounds which can be tolerated by P. monodon are:
|Un-ionized ammonia (NH3)||- 0.0–1.0 mg/l|
|Ionized ammonia (NH4+)||- 0.0–0.5 mg/l|
|Nitrite (NO2)||- 0.0–6.0 mg/l|
|Nitrate (NO3)||- 0.0–200 mg/l|
2.6 Hydrogen sulfide (H2S)
Hydrogen sulfide (H2S) in the pond is the result of the chemical reduction of organic matter which accumulate on or in the pond bottom. This is characterized by the presence of black color of the soil and a rotten odor is emitted. Shigueno (1975) observed that P. japonicus lost equilibrium when exposed to a level of 0.1 to 2.0 ppm hydrogen sulfide in water. The shrimp died instantly at a concentration of 4 ppm.
The accumulation of H2S could be avoided by periodic drying of the pond bottom and cultivation of the pond soil to expose the same under the sun until it hardens and cracks to dryness.
3. POND MANAGEMENT
Pond management is the cultural practice applied to attain the optimum production in a given area. This includes several activities prior to rearing and during the cultivation process.
3.1 Pond preparation
Any pond whether nurseries or grow-out ponds should be thoroughly prepared prior to the arrival of the stock. Pond preparation undergo several treatments such as:
3.1.1 Draining and drying
Complete draining of pond water and allowing it to dry for about a week or more depending upon the weather conditions prevalent in the locality. The reason for drying is to mineralize the organic materials which builds up in the soil, thus make the nutrients available for plant growth. It also reduces the production of H2S and other harmful substances that may come up during anaerobic reduction of the organic materials when the pond is full of water.
Other activities that are undertaken during drying are: repair of dikes and canals; turning over of the soil and levelling of pond bottom; and repair and screening of gates.
3.1.2 Improve or control acid sulphate soils
One method of improving pond with acid sulphate soils with pH less than seven is the repeated filling up and draining out of water in the pond. Another method is by the use of lime. For soils with pH 5, treatment with 3 tons per ha of agricultural lime has been effective. The lime can be worked into the soil by the use of hand-pulled harrow or a hand tractor.
3.1.3 Eradication of pests and predators
Prior to stocking all unwanted pests and predators have to be eradicated. The poison used is from organic pesticide such as saponin or rotenone at a rate of 10 ppm and 4 ppm, respectively. Flushing of the pond after treatment is undertaken to fully clean up the pond of undesirable organisms. This could only be effective if the gates are properly screened.
3.1.4 Pond fertilization
For better growth of algae, the pond is fertilized with chicken dung or other manure. This is applied to the dry pond bottom at the rate of 350 kg/ha. The chicken manure should be dried and not treated with insecticide. If no manure is available, inorganic fertilizer can be used; one or two 50 kg bags of 18–46–0 (NPK) or two or three 50 kg bags of 16–20–0 per ha.
3.1.5 Pond watering
Immediately after fertilization, 3–5 cm of water is let into the pond. After one week, the same amount of fertilizer is applied and the water level is raised to 10 to 15 cm. Fertilization is repeated after the second week and the water level is raised to 20 to 25 cm. Additional water is added to make up for losses by evaporation.
3.2 Pond stocking
The practices for stocking are as follows:
3.2.1 Time and method of stocking
The best time for stocking is during the colder parts of the day, in the morning or early evening. Before the seeds are released, it is advisable that the temperature and salinity of the water in the container and the pond water where they will be stocked be almost the same. This is done by floating the plastic bag or container on the pond water for at least 30 minutes. After the conditions in the bag and that of the pond are almost the same, the bag is opened and lower into the water. The seeds are allowed to swim out until all seeds are out of the bag.
3.2.2 Stocking rate
The stocking capacity of a pond depends on the farmer's management capability, type of management, cost of inputs and marketing strategy. A farmer has to decide what size of shrimp he wants to harvest and estimate how many kilogram per hectare he can produce per crop. Based on type of management, the stocking rates are as follows: traditional method, less than 2.0/sq m; semi-intensive, 2–4/sq m; and for intensive, more than 10/sq m for P. monodon. In other countries like the Philippines, a stocking density of 20 000/ha is used by some farmers.
3.3 Grow-out culture practices
The success in production depends on several culture practices. These include proper water management, correct stocking density and feeding technique. A brief discussion on the practices are as follows:
3.3.1 Water exchange
In ponds with static water, accumulation of waste products or depletion of trace metals or organic compounds can have a harmful effect on shrimps. Therefore, water should be changed as often as possible.
In traditional method of shrimp culture changing water is done every high tide; and the depth of pond water should be maintained at 30 to 50 cm above the pond bottom or 80 to 100 cm from the peripheral canal bottom.
For semi-intensive operations, 20 percent of water is changed during high tide or water change is done every 3 days with the use of water pump. Pond water is maintained at 50 to 75 cm depth.
On the other hand, in intensive culture, the pond bottom is provided with a sand substrate and water circulation is effected by a flow through system. Aeration devices are often used such as paddle wheels.
3.3.2 Monitoring of stock and water quality
Random sample of shrimp is collected with a cast net every 15 days. The shrimps are measured individually in length and weight to monitor the growth and determine the appropriate feeding levels.
Water temperature and salinity are monitored daily, for semi-intensive culture practices. Other water quality parameters monitored are water dissolved oxygen, total organic matter, pH, nitrate and ammonia. Water temperature and salinity are measured daily at 8:00 A.M. and 5:00 P.M. Other parameters are measured every seventh day.
In semi-intensive culture, additional application of fertilizer to support the growth of natural food in the pond is carried out. This is about 10 percent of the amount applied in the initial pond fertilization. Fertilizer used are urea (47-0-0), triple superphosphate (0-35-0) and organic fertilizer.
3.3.4 Installation of aeration system
Most common aeration system used in shrimp pond is the paddle wheel. The ideal number of paddle wheel in a hectare of pond is 4 pieces of 1 to 1.5 hp each. At the early stage of the cultivation, this is used for 8 hours between 11:00 o'clock in the evening and 6:00 o'clock in the morning. However, at near harvest this is operated for about 18 hours per day between 8:00 o'clock in the evening to 8:00 o'clock in the morning and at 11:00 o'clock in the morning to 3:00 o'clock in the afternoon. The aeration system is a must in either the semi-intensive or intensive shrimp cultivation.
3.3.5 Feeds and feeding
In the cultivation of shrimp, feeding is necessary in either the semi-intensive or intensive shrimp culture. The feeds are given either twice, thrice or four times a day. The rate of feeding ranges from 5 to 10 percent of the biomass.
For semi-intensive culture, supplementary feeds are given two weeks or after a month when the natural feeds are almost exhausted. These may consist of ground trash fish, mussel meat, shrimp heads and other feed formulations available in the market.
For intensive shrimp culture, commercial formulated feeds are often used. Feeds are given immediately on the start of the cultivation.
Sample of feed frequency: feeds estimated per day for the first two months are given twice a day; 40 percent would be given at 7:00 A.M. and the rest or 60 percent given at 5:00 P.M. For the next month, thrice a day, 30 percent at 7:00 A.M., 30 percent at 10:00 A.M. and 40 percent of the estimated feed at 5:00 P.M. In the last and fourth month, 20 percent at 10:00 A.M., 40 percent at 5:00 P.M. and the rest of the feeds at 10:00 P.M. Table 1 shows the composition of formulated feed for P. monodon.
Table 1. Composition of formulated feed for Penaeus monodon
|Average body weight of shrimp||Feed type||Shape of feed||Moisture|
3.4 Method of harvest
Generally, behavioral characteristics of shrimps are taken into account during harvest. These are: moving around the pond at night looking for food; attraction to light; stimulated by water current; often gathered near sluice gate; and bigger shrimps swim out of the pond with the water when water is discharged. With these tendencies, farmers can devise equipment for harvest of stock. Some of the harvesting gears and methods used are discussed below.
3.4.1 Barrier trap
This type (see Figure 1) is set around the edge of a pond about 2–5 meters from the gate. This is used at night. No bait is needed. A small kerosene lamp is placed on top of the trap to attract the shrimp.
Cast net, lift net and seine net can be used to harvest shrimps partially. Bait or food are also set for effective harvest.
3.4.3 Electric shrimp catching
The gear is composed of an accumulator and two bamboo poles. One of the poles is equipped with a metal tip and the other has a steel ring with a net attached. The metal tip is connected by wire to the anode of the accumulator and the steel ring to the cathode. The accumulator is carried in a backpack as on a small raft and the operator holds one pole in each hand as he wades through the pond. When the gear is switched on, an electric field is formed between the two poles, on receiving an electric stimulation, the shrimp jump out of the water and are caught in the net.
3.4.4 Bag net
Most species of shrimp can be harvested effectively by using the bag net placed in the sluice gate and catching the shrimps as they swim out with the outflow of water. Figure 2 shows a picture of the operation of the bag net.
Figure 1. Trap for use in a shrimp pond
Figure 2. Harvest net with lazy line-arrows water flow
3.4.5 Manual method
Manual method is generally used for complete harvest. The pond is drained very slowly until water remain in the canals. The shrimps in the canal are removed by means of seine net, scissor and drag net.
Anonymous. 1978 Manual of pond culture of penaeid shrimp. With the assistance of the FAO/UNDP South China Sea Fish. Dev. & Coord. Prog., Manila. Asean National Coordinating Agency of the Philippines. Ministry of Foreign Affairs, Manila, Philippines, 132 pp.
Aquacop. 1977 Reproduction in captivity and growth of Penaeus monodon Fabricius in Polynesia. Paper presented at the 8th Annual Workshop of the World Mariculture Society.
Cook, H.L. 1976 Problems in shrimp culture in the South China Sea Region. South China Sea Fish. Dev. & Coord. Prog., Manila, SCS/77/WP/40:29 pp.
Delmendo, M.N. and H.R. Rabanal. 1956 Cultivation of sugpo (Jumbo tiger shrimp), Penaeus monodon Fabricius in the Philippines. Proc. Indo-Pacific Fish. Coun, 6 (2–3): 423–431.
Liao, I.C. 1977 A culture study on grass prawn, Penaeus monodon in Taiwan: The patterns, the problems and prospects. Journ. Fish. Soc. of Taiwan 5 (2): 11–29.
Liao, I.C. and T.L. Huang. 1982 Status and prospect of the culture of two important penaeid prawns in Asia. Presented at IV Simposio Latinoamericano de Aquacultura, Atlapa, 25–29 January, 1982. 32 pp.
Liu, M.S. and V.J. Mancebo. 1983 Pond culture of Penaeus monodon in the Philippines: Survival, growth and yield using commercially formulated feed. San Miguel Corporation Agri-Business Project Group, Makati, Metro Manila, Philippines, 27 pp.
Shigueno, K. 1975 Shrimp culture in Japan. Assoc. for International Technical Promotion, Tokyo, Japan. 153 pp.
Training Director, Training Committee Brackishwater Aquaculture Development Centre Jepara, Indonesia
Many organisms may act as predators, competitors or cause diseases to shrimps. Some organisms known as the main predators for shrimp are as follows: fish, crabs, birds, snakes, etc. while fish, wild shrimp, snails, small crabs and worms can act as competitors. On the other hand shrimp also suffer various kinds of diseases caused by viruses, bacteria, fungi, protozoea and other diseases caused by nutritional and environmental factors.
2. GENERAL METHODS TO PREVENT OR CONTROL PESTS AND DISEASES
2.1 Prophylactic measures
Preventive methods to avoid pests and diseases could save losses in shrimp farming. Prophylactic measure is aimed to prevent shrimps from contact with pests and diseases.
Such measures can be divided into the following:
2.1.1 Protection to prevent the pest and disease pathways into the culture system, which includes:
2.1.2 Preventive measures to strengthen animal resistance includes:
2.2 Therapeutic/treatment measures
This is an attempt to eliminate pests and diseases in the culture system or to recover shrimp from diseases by:
3. METHODS OF CONTROL OF PREDATORS AND COMPETITORS
Several ways to overcome fish predation problems in shrimp pond culture are as follows:
3.1.1 Natural products
a) Saponin. Saponin is now known as the best compound to poison fish without damaging the shrimp or food organisms in the pond. It is 50 times more toxic to fish than to shrimp, so it is safe to use while the shrimps are in the pond. It is sold in cake form, a residue from the processing of oil from the seed of Camelia, which contains 10 to 15 percent of saponin. The rate of application is about 10 ppm (10 kg per hectare of average water depth 10 cm). This rate is effective to kill eels. The cake must be ground up and soak in water for 24 hours before use.
b) Rotenone. Rotenone has also been used to selectively kill fish but not shrimp. Rotenone is available in the form of powder or Derris root. The powder usually contains 5 percent of rotenone, it is the most effective and easiest one to use. It requires 4 ppm to kill fish and double dosage to kill eels. Rotenone content of the root varies with the quality of the root. This makes the application dose also vary between 4 to 10 ppm. To use the root, it should be cut into small pieces and soaked overnight in water then pound to crush and squeeze the juice out into the water where the root was soaked in.
c) Tobacco dust. Tobacco dust is also toxic to shrimp, it is used only in pond preparation prior to stocking. The application is done by broadcasting over the dry pond bottom at a rate of 200 kg per hectare.
3.1.2 Manufactured products
Many products are widely used such as KCN (Potassium cyanide) at a rate of 0.1 ppm, PCP-Na (Sodium pentachloropenate) 0.5 ppm, Thiodan 0.5 ppm and several others. Due to the less selective nature of these chemicals, special care should be taken in their use. It is recommended to use only when there are no shrimps in the pond.
The presence of crabs in the ponds can be resolved by:
Traps baited with fish, snake, toads or uncooked bones.
Sevin insecticide mixed with ground up fish; small ball of the mixture are placed in crab holes above the water line. It is also possible to put the fish balls in the crab holes below the water line, then close the hole.
Calcium carbide is put into crab holes and enough water poured in to wet the carbide and produced acetylene gas which kills crabs.
Tobacco dust, Brestan and Aquatin can kill on direct contact.
Snails in shrimp ponds cause reduced pond productivity, to avoid this problem there are two methods:
Hiring people to manually harvest the snails.
The commonly used chemicals are Brestan and Bayluscide at a rate of 0.5 ppm. However, shrimp production is reported to be delayed by six months after the use of Brestan.
Birds in shrimp rearing pond can affect heavy losses of shrimps especially when they are schooling. To avoid this problem, there are some ways such as:
Flashing mirror to scare birds away from ponds.
Shooting or trapping.
Hanging a dead bird that could be seen by other birds so it will discourage new birds from entering the ponds.
4. SHRIMP DISEASES
Disease may be defined as a definite morbid process that can affect the whole body or any part of it. The disease etiology, pathology and prognosis may be known or unknown. It can be observed physically.
It should be realized that although the knowledge of shrimp diseases is advancing, the information available is still inadequate. Information on shrimp disease is largely based or records of clinical observations rather than from experimental studies under pond conditions.
From the etiological point of view, shrimp disease may be classified as pathogenic and nonpathogenic diseases as follows:
Pathogenic disease caused by viruses, rickettsia, bacteria, fungi, protozoea worm, etc.
Nonpathogenic diseases such as blackgill disease, body cramp, muscle necrosis and many other nutritional or toxicological diseases.
Since not much is known about shrimp diseases prevention must be considered as the first action of disease control in aquatic animals.
Some information about penaeid shrimp diseases are presented on the following notes.
4.1 Viral diseases of penaeid shrimp
|Agents||:||Infection Hypodermal and Hematopoietic|
|Necrosis Virus (IHHNV)|
|Gland Necrosis Virus|
|Size of virus||:||20–300 μm|
|Life stages affected||:||All life stages|
|Part of shrimp body||:||Hepatopancreas|
|Diagnosis||:||Demonstration of inclusion bodies|
|Electron microscopy methods|
|Conditions stimulating infection||:||Crowding and stress|
|Sign of infection||:||Weakness of body|
|Erratic swimming, paralysis and sinking|
|Slow growth, poor food conversion|
|Abnormal chromatophore distribution|
|Transmission||:||Horizontally and vertically|
|Prevention and control||:||Use of quarantine|
|Elimination of infected shrimp|
|Disinfection of culture facilities|
|Reduction of density and stress|
4.2 Rickettsial disease of penaeid shrimp
|Agents||:||Rickettsia or rickettsialike microorganism|
|Size||:||0.2–0.7 × 0.08–1.6 μm|
|Life stages affected||:||Juvenile to adult|
|Part of shrimp body||:||Hepatopancreatic epithelium|
|Connective tissue cells|
|Diagnosis||:||Microscopic or histologic methods|
|Sign of infection||:||Slow growth|
|Poor food conversion|
|Prevention and control||:||Elimination of infected shrimp|
4.3 Bacterial diseases of penaeid shrimp
|Life stages affected||:||All life stages are susceptible|
|Parts of shrimp body||:||Internal, specific or localized|
|Appendage and gill|
|Any suspect of shrimp surface|
|Isolation of identification|
|Condition stimulating infection||:||Exposure of shrimp to severe stress|
|Sign of infection||:||Erratic swimming|
|Expansion of chromatophores|
|Darken color of body|
|Anorexia and lethargy|
|Abnormal body formation|
|Transmission||:||From culture environment|
|Horizontally and vertically|
|Prevention and control||:||Suitable density|
|Water quality management|
|Treatment of antibiotic|
|(in separate table)|
4.4 Fungal diseases of penaeid shrimp
|Life stages affected||:||Larval to postlarval stages|
|Parts of shrimp body||:||All parts|
|Diagnosis||:||Microscopic demonstration of branched fungal hypae|
|Culture on agar added by antibiotics|
|Sign of infection||:||Acute mortality of larvae|
|Demonstration of banana-shaped macroconidia of Fusarium sp.|
|Transmission||:||Zoospores/macroconidia from detritus, organic matter, infected larvae or broodstock|
|Prevention and control||:||Strict sanitation|
|Elimination of infected larvae|
|Drug/chemical treatments (in separate table)|
4.5 Protozoal diseases of penaeid shrimp
|Many kinds of ciliates|
|Life stages affected||:||Late larval stage through adult|
|Parts of shrimp body||:||All parts especially eyestalk and uropods Internal tissues|
|Condition stimulating infection||:||Detritus and high organic matter content on the bottom of culture tanks|
|Sign of infection||:||Poor growth|
|Poor feed conversion|
|Fuzzy appearance of heavily infected shrimp|
|Various episodes of mortality|
|Transmission||:||From culture environment|
|Prevention and control||:||Filtration and disinfection of incoming water|
|(in separate table)|
4.6 Body cramp
|Agents||:||Environmental or nutritional factor(s), i.e. high temperature|
|Life stages affected||:||Juvenile to adult|
|Parts of shrimp body||:||Third abdominal segment|
|Parts of shrimp body||:||Gross observation of shrimp with rigid, dorsal flexture of the tail|
|Prevention and control||:||Careful handling|
4.7 Muscle necrosis
|Sudden salinity or|
|Severe gill fouling|
|Life stages affected||:||All life stage|
|Diagnosis||:||Demonstration of gross and microscopic lession of muscle necrosis|
|Sign of infection||:||Loss of transparency of the striated muscle of shrimp|
|Prevention and control||:||Reduction or elimination of stress|
4.8 Black gill diseases
|Agents||:||Exposure to toxic levels of cadmium, copper potassium permanganate, ozon, crude oil, low pit, ammonia, nitrite, etc.|
|Life stages affected||:||Juvenile to adult|
|Parts of shirmp body||:||Gill|
|Diagnosis||:||Demonstration of melanized gill Black discoloration of the gill|
|Prevention and control||:||Use filter|
|Frequent changes of water|
List of drugs used for treatment of diseases of shrimps
|Number||Drugs and dosage||Life stage||Targets|
|25 ppm for 1 hour||L/J||Ext protozoa, nematode Disinfection|
|50 ppm for 3 hours||B|
|2.||EDTA||L/PL||Chelating agent Disinfection|
|3.||Malachite green||L/PL||Fungi and protozoa|
|1.5 g/kg feed for 2 weeks|
|500 mg/kg feed for 2 weeks||J/A|
|500 mg/kg feed for 2 weeks||J/A|
|500 mg/kg feed for 2 weeks||J/A|
|19.||Cutrine plus||L/PL||Filamentous bacteria|
|0.5 ppm for 24 hours|
L — Larvae
PL — Postlarvae
J — Juvenile
A — Adult
B — Broodstook
Sri Umiyati Sumeru
Brackishwater Aquaculture Development Centre
Tiger shrimp (Penaeus monodon Fabricius) is one of the important fishery export commodities, especially for the countries having mangrove forest area which is suitable to develop for brackishwater ponds. In traditional brackishwater pond culture, the production of shrimp from the ponds is secondary to milkfish farms. The seeds enter the ponds through the incoming tide water.
With the advances gained in the techniques of shrimp farming there has been considerable expansion in the development of shrimp farming. Intensification of shrimp farming operations need supplemental feeds.
Based on consideration stated above, this paper describe the techniques of processing of artificial feeds which is suitable for penaeid shrimps.
2. NUTRITIVE VALUE REQUIREMENTS
Principally, the nutritional need of the shrimps is qualitatively the same as in other animals, although there are some specific differences in the diet formulation. The nutrients needed are protein, fatty acid, carbohydrates, vitamins and minerals. The composition of formulated feeds for shrimp are presented in Table 1.
Proteins are the complex organic compounds which are essential in the structure and functioning of plants and animals. Proteins are composed mostly of amino acids linked with peptide bonds and cross linked between chains with sulphydral and hydrogen bonds. There are twenty major amino acid bonds. Amino acids contain different amounts of nitrogen. Thus, figures given for protein level in feed compositional tables are never fully accurate. For crustaceans and fish the essential amino acids (EAA) are arginine, histidine, isoleucine, leucine, lysin, methionine, phenylalanine, threonine, tryptophan and valine (Table 2). If the essential amino acid requirements of shrimp are known, it should be possible to meet these needs in culture systems in a number of ways from different food proteins or combinations of food proteins.
Table 1. Composition of formulated feed for shrimp
|Nutrient content||I||Type of feed (diet)|
|Energy (K Cal/kg)||%||3 300–3 500||3 000–3 300||2 700–3 000|
I - Shrimp size (PL20± 1 gram)
II - Shrimp size (± 1 gram- 10 grams)
III - Shrimp size (10 grams- > 35 grams)
Table 2. Composition of essential amino acids for Penaeus monodon Fabricius
|Kinds of essential |
|Percentage contents |
Some sources of proteins which are good for shrimp diet are fish meal, squid meal, shellfish meal, shrimp head meal. These can be entirely substituted for each other without a reduction in food conversion rate for fish and shrimp.
2.2 Fat (lipids)
Lipids are organic matter containing carbon, hydrogen and oxygen which are undissolved in water, but are dissolved in ether, chloroform and benzene. Lipids consist of fatty acids and alcohol. The characteristics of lipid are determined by fatty acid composition. Fats are the fatty acid esters of glycerol and are the primary energy depots of life of organisms which are used for long term periods of extensive exercise or during periods of inadequate food and energy intake. Dietary linolenic, arachidonate and linoleate acid (PUFA) gives a positive growth response for penaeid shrimp which may be attributed to a dietary requirements for W3 fatty acids. Good dietary fatty acids for penaeid shrimp can be prepared from cod liver oil and soybean oil at 3:1 ratio.
Carbohydrates are energy source nutrients containing carbon (C), hydrogen (H) and oxygen (O) with different rates of exchange. These are present in a broad group of substances which include the sugars, starches, gums and celluloses.
The simplest carbohydrates are the three carbon sugars which figure importantly in intermediary metabolism and the most complex are the naturally occuring polysacharides primarily of plant origin. These are present in animals as glycogen, sugars and their derivatives.
Penaeid shrimps need different kinds of carbohydrates. Fish and shrimp could effectively utilize up to 60 percent glucose, sucrose or lactose in the diet. This demonstrates that contrary to earlier belief, carnivorous animals are capable of efficiently utilizing simple carbohydrates as a primary energy source. Examples of raw material sources of carbohydrates are rice bran, cassava meal, corn meal, sago flour, glutinous rice meal, rice meal, etc.
2.4 Vitamins and minerals
Only a little information about the quantity of vitamins and minerals for penaeid shrimps is known. Vitamin deficiency can affect the growth of shrimp. Vitamins are divided into two: water soluble vitamins and fat soluble vitamins. Water soluble vitamins are: B complex, Thiamine, Riboflavin, Pyridoxine, Pathogethenic acid, Niacin, Biotin, Folic acid and Vitamin B 12. Fat soluble vitamins are: Vitamins A, D, E and K. They differ from the water soluble vitamins in their accumulative action. Mineral elements have great diversity of uses within the animal body. Penaeid shrimp needs mineral elements essential for body function such as calcium, phosphorus, sodium, molybdenum, chlorine, magnesium, iron selenium, iodine, manganese, copper, cobalt and zinc, but the total limit of mineral is still unknown and have to research on it. Examples of raw material sources of vitamins and minerals are: aquamix, top mix, choline, insitol, thyamine, pyridoxine, B complex, ascorbic acid and de col phosphat.
3. FEED PROCESSING
Principally, formulated feed for shrimp is divided into powder, flakes, crumble and pellets which is used according to the stage of growth of the shrimp. Specification of these feeds are presented in Table 3.
Table 3. Type of feed for penaeid shrimp
|Type of feed||Size of feed particle||Stages of shrimp|
|Powder||Less than 20 micron||Larval stages|
|Flakes||Less than 0.5 mm||PL1-PL15|
|Crumbles||Æ 1 mm||PL20-1 gram|
|Pellet I||Æ 1-1.5 mm||1-5 grams|
|Pellet II||Æ 1.5-3.5 mm||5-10 grams|
|Pellet III||Æ 3.5-5.0 mm||7/10 grams|
There are six steps in formulated feed processing, i.e.: grinding and pulverizing, sieving, weighing, mixing, shaping and drying.
3.1 Grinding and pulverizing
The first step in feed processing is grinding and pulverizing to make fine particles by means of grinder, micropulverizer or traditional method of pounding process with a pestle.
The second process is sieving the ground materials to get very fine particles by using a sifter of less than 100 microns. The smaller the particles the better as the feed could be more compact for making formulated feed.
Prior to making artificial feed, all materials previously screened should be weighed by means of a beam balance. The vitamins and minerals are weighed by the use of analytical balance because of the minute quantities required.
The next step is mixing of all materials weighed. This can be done manually by hand or by using a mixer to be homogenously mixed.
Table 4. Types of equipment necessary for the production of different kinds of aquaculture feeds*
|Mash meal||Floating pellets||Sinking pellets||Granules||Extruded||Pastes, cakes and balls||Nonformed|
|Grinder/Mill (dry products)1||+||+||+||+||+||+||-|
|Grinder (wet products)||-||-||-||-||+||+||+|
|Pelleter and dies||-||-||+||+||-||-||-|
|Mincer/Extruder and dies||-||-||-||-||+||?3||-|
|(Expanders) and dies||-||+||-||-||-||-||-|
1 Not needed if all dry products purchased in ground form.
2 Manual labour can substitute, especially in smaller plants.
3 Feed balls sometimes formed from extruded products.
4 Only if product not used moist.
5 Not in ‘cold’ process.
6 Only if product not to be used immediately.
* Source: ADCP/Rep/87/26.
Type of feed shape is dependent on kind of machine used. Pellet machine or CPM pellet mill can be used for making pellet, and the product can be made to crumble by using crumble machine. Flake feed is processed by the use of electrosteam and double drum dryer. Table 4 shows the types of equipment for the production of different kinds of feeds.
3.6 Drying and packaging
After processing, the product should be dried until water content of the product is less than 10 percent. This can be dried in an oven at certain temperature or dried under sunlight. After this process, the product is then packaged by using plastic bag or other containers.
For further reading and more comprehensive reference on feeds preparation for fish and shrimp, ADCP/Rep/87/26 is recommended. This document was prepared by FAO in 1987, entitled Feed and Feeding of Fish and Shrimp - A Manual on the Preparation and Presentation of Compound Feeds for Shrimp and Fish in Aquaculture. Michael B. New, 1987. FAO, Rome.
Anonymous. Fish feed technology. 1978 Lectures presented at the FAO/UNDP Training Course in Fish Feed Technology held at the College of Fisheries, University of Washington, Seattle. Washington. 9 October-15 December 1978, FAO. 395p.
Catedral, F.F. and Veronica A. Dy Penoflorida. 1977 Quarterly Research Report, 4th Quarter (October-December). Volume 1, No.4. Aquaculture Department, SEAFDEC, Tigbauan, Iloilo, Philippines.
Sumeru, S.U. dan Kusnendar 1987 Teknik Pembuatan Pakan Udang Penaeidae. INFIS Manual Seri No. 50, 1987. 26p.
Formulated feeds for penaeid shrimp
|- Rice bran||22 percent||Nutritive contents|
|- Cassava meal||21 percent||Protein||35.65 percent|
|- Fish meal||31 percent||Lipid||7.67 percent|
|- Soybean meal||25 percent||NFE||41.48 percent|
|- Vitamin C||50 mg|
|- Vitamin B1||15 mg||Ash||9.36 percent|
|- Vitamin B6||10 mg||Moisture||6.84 percent|
|- Aquamix||425 mg|
|- Fish meal||26 percent||Nutritive contents|
|- Head shrimp meal||10 percent||Protein||33.42 percent|
|- Soybean meal||15 percent||Lipid||6.35 percent|
|- Corn meal||15 percent||NFE||32.95 percent|
|- Cassava meal||15 percent||Crude fiber||8.64 percent|
|- Rice bran||13 percent||Ash||12.43 percent|
|- Top mix||2 percent||Moisture||6.21 percent|
|- Liver oil||2 percent|
|- De cal phosphat||2 percent|
|- Fish meal||40 percent||Nutritive contents|
|- Small shrimp meal||8 percent||Protein||36.27 percent|
|- Soybean meal||10 percent||Lipid||5.21 percent|
|- Corn meal||20 percent||NFE||39.43 percent|
|- Sago flour||16 percent||Crude fiber||0.43 percent|
|- Top mix||2 percent||Ash||14.42 percent|
|- Liver oil||2 percent||Moisture||4.24 percent|
|- De cal phosphat||2 percent|
|- Fish meal||31 percent||Nutritive contents|
|- Squid meal||5 percent||Protein||34.21 percent|
|- Soybean meal||15 percent||Lipid||5.43 percent|
|- Corn meal||15 percent||NFE||35.44 percent|
|- Glutinous rice meal||18 percent||Crude fiber||6.42 percent|
|- Rice bran||10 percent||Ash||13.07 percent|
|- Top mix||2 percent||Moisture||5.43 percent|
|- De cal phosphat||2 percent|