The cultivation of biological feeds plays a crucial role in shrimp aquaculture. The advantages of adopting cultured biological feeds for raising shrimps are: fast growth of shrimps, individual fertilizers, large specifications, and good cultivation of biological baits not only solve the shortage of animal feed, but also save some artificial feed, reduce production costs, and improve economic efficiency. At the same time, it also reduced water pollution, purified the aquaculture water environment, reduced the incidence of shrimp, and improved the quality of shrimp.
Shrimp tanks can be used as biological feed usually have the following types: leeches, rotifers, Artemia and nauplii, sand and biological sediments.
1. Blister leeches are commonly known as red worms. Aquatic leeches are two types of zooplankton in aquatic cladocera and copepods. They are rich in nutrients and easily digested. They are good natural feed for juvenile shrimp and contain abundant protein and oil. Can promote the rapid growth of juvenile shrimp and increase the resistance of shrimp to disease. The leeches have a large amount of breeding, a short growth cycle, a low food level and a rapid growth, and are good natural feeds for artificial cultivation.
(1) Culture conditions: The suitable water temperature for leeches growth is 15°C~25°C (the optimum water temperature is 18°C~20°C). It is suitable for weak light and daily light for 9 hours to 15 hours. The pH value is 7 Between ~8, the saturation of dissolved oxygen should be 7%~12%, and the oxygen consumption of organic matter should be 20 mg/l.
(2) Culture method: When the water temperature reaches 15°C, the shrimp pond is filled with 50cm to 60cm of water, 100g of lime must be used for disinfection per square meter, and 100 mesh mesh filter is used for water intake, and the fermented mixture is then mixed. Compost (chicken excrement, cow dung, horse dung) is fertilized at 100 kg to 150 kg per acre, allowing bacteria and algae to multiply. During the breeding process, topdressing urea or nitrogenous fertilizer and phosphate fertilizer once a day, each topdressing nitrogen fertilizer 2 g/m3, phosphate 0.2 g/m3. Dry yeast can also be put in the breeding process, 20 grams per cubic meter, dry yeast should be soaked in water for 3 hours to 4 hours. After 2 weeks to 3 weeks, shrimp ponds can reach a certain amount.
2. The rotifer rotifer is a small aquatic animal that has the characteristics of fast growth and strong fertility. Its small size, swimming speed and nutritional value are very suitable as the open feed for prawn larvae.
(1) Clearing ponds: The ponds must be cleared before entering the pond. Freshly-digging shrimp ponds can directly enter the water; if the old ponds should drain water, the remaining pond water should be given a drug clearing pond to kill fish and crustaceans. Qingchi drugs can be used: 1 bleaching powder: the use of 30% chlorine content of bleaching powder is 25 g/m2 to 30 g/m2, the general efficacy of 3 days to 5 days disappeared. 2 Fish rattan: Advanced water 40 cm to 60 cm, with 2 g/m3 of fish pond fine clear pond. After clear ponds, the filtered seawater can be filtered. The sieves are screened with 160 mesh to 200 mesh to prevent the entry of predator organisms. Adjust the salinity to 10‰ to 20‰, and fertilize it to make the water eutrophic.
(2) Fertilizer: After clearing the pond, the fertilizer can be added into the water. Fertilizers are commonly used organic fertilizers and inorganic fertilizers. The application amount is determined according to the conditions of the pool water. The amount of fertilizer used is generally 3 g/m3 of superphosphate, 15 g/m3 to 20 g/m3 of urea, and 200 g/m3 of human urine. Chicken manure and duck dung are due to their large fertilizer effect and strong persistence. The dosage is 200 g/m3, which should be fermented before use. You can dig a small pit near the pool, pour the manure into it, then cover it with a plastic film and press it around with earth. After 1 week of fermentation, it can be poured into the pool around noon every day.
After fertilization, usually under light and good temperature conditions, the water color usually changes from light green to light brown after 3 to 5 days.
(3) Inoculation of rotifers: When the natural water temperature reaches around 10°C, the rotifers can be vaccinated at a suitable time when the pool water is rich, and the rotifers can also be purchased from the nearby greenhouses, but the egg-laying rate is required to be high. When inoculating, select the highest temperature in sunny afternoon. Inoculum density: 10 or litres of live rotifers or high-density seeding depending on the situation.
After rotifer inoculation, in the early stage of culture, due to the large amount of base fertilizer, and the lower temperature of the water, it is generally not necessary to supplement fertilizer or a small amount of supplement fertilizer. In the later period, algae reproduction is accelerated as the water temperature rises, and the nutrient consumption in the water body needs to be promptly replaced. fat. Supplementing fertilizer is generally performed before and after noon, and the amount depends on the quality of the water. Pay attention to a small amount of work.
3. Artemia and its nauplii Artemia nauplii is rich in protein and a large amount of fat, and individual size (about 0.5 mm) is moderate, which can be used as a good feed for juvenile and adult shrimp. Artemia in the shrimp ponds can be cultured with Artemia eggs, and live egg-feeding Artemia can also be inoculated.
(1) Preservation of eggs: Storage and storage under conditions of vacuum (water content of eggs lower than 9%), eggs can be preserved for a long period of time, hatching rate of eggs of Artemia in two or three months at room temperature. It is necessary to reduce, cryopreservation can extend the survival time of eggs, but eggs stored at low temperature must be kept at room temperature for 1 week to 2 weeks before hatching, otherwise it will reduce the hatching rate.
(2) Inoculation of Artemia eggs: After the shrimp pool clears the water, first fertilizes and reproduces the monocellular algae. When the transparency of the pool water reaches 30 cm to 40 cm, the eggs of Artemia are fed, and after 2 weeks to 3 weeks, the shrimps are injected. .
4. Nereis Nereis is an important food for fish, shrimp and other animals. Since many types of sand flesh material are large in size, they can be bred in the shrimp ponds and feed on the bottom layer of detritus and small organic matter, and are therefore favored by shrimp farmers. The basic approach is: In the breeding season of the silkworm, the silkworm eggs and larvae are introduced into the shrimp pond. Under the artificial cultivation, the basic bait, the larvae of the silkworm silkworm, and the shrimp seedlings are grown in the same water environment, and are mutually utilized. An ecosystem forms an artificial biological chain relationship. That is, the basic food in the feeding pond of the larvae of the silkworm larvae, the organic substances and the residual larvae depend on it for survival, and in itself, it becomes a live feed for the cultured prawn.
The technical points are:
(1) According to the local species, quantity, distribution, living habits, breeding season and other factors of the Nereis, grasp the peak period of oviposition of the Nereis, in order to prepare for the timely admission of water.
(2) According to the habit of living in the loose, clean pool bottom of the silkworm, the shrimp should be sealed in the drying area immediately after the shrimp is harvested. Before the Spring Festival, the sludge should be removed and the bottom of the pond should be plowed. The depth should be 15 cm to 20 cm.
(3) When the gate is opened, the nets or water can be lifted, and the silkworm eggs and larvae can enter the shrimp pond. Under normal circumstances, the density of eggs and larvae in the tidal water and downpour water is large. Many times the water is better than the one-time water supply. The water with a large amount of water is better than the water with a small amount of water. The effect of undrained drainage is better. , Into the water network to 60 mesh is appropriate.
(4) After the silkworm eggs and larvae enter the pool, a certain amount of inorganic fertilizer or organic fertilizer is applied according to the change of the water color; the density of the sandworm is large, and when the water is thin, the food bait should be timely fed to ensure the survival rate of the larvae of the silkworm, Rapid growth and high density submerged into the cave.
(5) Rationally use silkworms and give full play to the role of silkworms in bait. The best time for shrimp to use silkworms is after mid-August. One is that at this time the silkworm has grown up, and the average weight is 0.3 g to 0.5 g. The second is that the length of the prawn has reached more than 9 cm and it has the ability to feed a large number of sandworms. Third, after mid-August, it is the high-temperature period and easy-to-incidence period of shrimp rearing. The shrimps ingest large amounts of Nereis, the survival rate is high, and the incidence rate is low. Fourth, in order to avoid premature feeding of larvae of planktonic larvae, shrimps can be postponed for a suitable period of time, or the shrimps that have been reared for a period of time have the best effect. Fifth, after the shrimps are in the lower pool, the amount of feeding can be appropriately increased to solve the problem of competition between the silkworm and the shrimp seedlings. Sixth, after entering mid-August, in order to induce shrimp to feed on the silkworm, it is necessary to reduce the amount of bait in time. After the silkworm is eaten, shrimp should be collected in time.
5. Biological soil layer The biological soil layer is a special biological community mainly composed of benthic algae, which grows and grows on the bottom surface of the shrimp pond. The probiotics, nematodes, mollusk larvae, and autotrophic bacteria are common nutritional values. Comprehensive, it is an ideal feed for juvenile shrimp.
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