First, the choice and transport of broodstock
Broilers usually come from shrimp farming ponds, and are collected and cultivated in mid-to-late October. Several broodstocks should be watched as long as the standards are as follows: First, the individuals should be large and the specifications relatively neat. Generally, the females are required to be more than 10 cm long and heavy. 25-30 grams; Second, healthy and disease-free, bright body, normal activities, body fat, appendages to be complete, so in the selection process to be careful and careful, with water operation; Third, sex ratio is reasonable, in order to make broodstock A better fertilization rate is obtained, with a ratio of 3:1 for males and females. The number of reserved broodstock can be determined according to the individual size of the broodstock, the planned amount of the nursery production in the coming year, the survival rate in the wintering cultivation process, and the maturity of the nursery management technology. In accordance with experience, usually, each The tail of about 35 grams of female shrimp production to 2000 shrimp tail, survival rate of 80% of the winter arrangements.
The commonly used methods of transport of broodstock are the following: open canvas transport, canvas box specifications using 0.8 meters, 0.8 meters, 1.0 meters, transportation, depending on the water temperature and transport distance and flexible control. The water temperature is 20-23°C, and the transportation time is shorter than 5 hours. Each box can transport 20-30 kg of broodstock, and it is necessary to continuously inflate or oxygenate during transportation. The tin box transportation specification adopts 0.8 meters, 0.8 meters, and 1.2 meters. The broodstock is first placed in a shrimp box. The structure of the shrimp box is similar to that of a crab box. The specification is about 60 cm, 70 cm, and 12 cm. The shrimp box loaded into the broodstock is put in advance. In the tin box filled with clean water, 8 to 10 shrimp boxes can be placed in each tin box, and 5 to 8 kg of shrimp can be placed in each shrimp box. During transportation, it is necessary to continuously inflate or oxygenate. Nylon bag oxygenation transport, suitable for a small amount of broodstock transport, before the shipment of pro-fish shrimp need to cut off, each bag of water 8 kg, such as temperature 20-23 °C, transport time 4-5 hours, each bag can be loaded Shrimp 1.5-2.0 kg. Modern high-volume transport rules can be used with live water trucks, which are better.
Second, the cultivation and management of broodstock
Including overwintering management and pre-production strengthening and management. Broilers usually spend winters in fresh water, using glasshouses, plastic film sheds or deep well water insulation. The area of ​​broodstock wintering cultivation ponds is generally 50-100 square meters. Before the broodstock enters the pond, bleaching powder (15 grams per cubic meter) or potassium permanganate (100 grams per cubic meter) must be used for shrimp pond disinfection. The density of broodstock stocking is controlled at about 15-20 tails per square meter. The entire wintering period is generally from November to April in the coming year. The pre-natal strengthening cultivation is to be started at the end of February and early March. The management techniques are as follows:
1. Control water temperature: The water temperature in the early winter is best controlled at 20-23°C. During the prenatal culture stage, the water temperature should be gradually adjusted to 25-26°C. The temperature should be kept steady, and the daily temperature should be controlled within 3°C. At the same time, a shading facility is installed above the pool surface to avoid direct light irradiation.
2. Reasonable feeding: Feeds that can be fed during the early winter period include: fish and shellfish meat, bean cake, cooked barley, corn, etc. It can also be used with pellet feed. The daily feed amount is about 4% of the shrimp body weight. The amount of dry bait is 1%-2%; it is fed twice a day and is mainly fed once at night, accounting for 70% of the daily feeding amount. In the late winter, when the intensive cultivation period is in progress, it is necessary to increase the feeding of animal feed. The amount of daily feed also increased correspondingly to 5%-7% of shrimp body weight. Before the feeding, the residual bait should be removed, and the type and quantity of bait should be timely adjusted according to the specific conditions such as weather and food intake.
3, management of water quality: broodstock pool should have inflatable facilities, 50 square meters of shrimp pond every 2-4 square meters need to put a gas stone, intermittent air inflation during the day, should be continuously inflated at night, so that the dissolved water in the shrimp pond water at least remain in 3 mg/l or more. Sewage should be collected every day, and the water should be changed regularly. Generally, the wintering pond should be replaced by water for 5-7 days. The amount of water exchanged should be 1/3-1/2. When entering the intensive cultivation, the number of water changes should be increased, but the change of water should be strict. Note that the temperature change, the hourly temperature difference should not exceed 1 °C, where conditions can be exchanged into room temperature to 20-23 °C or 25-26 °C preheated water.
4, to prevent disease: broodstock disinfection before entering the pool, the shrimp body must be disinfected; in the cultivation and management process will often check the activities of broodstock activities such as feeding, and once every 15 days use of antibiotics, Quanchiposa sterilization Oxytetracycline dosage is 1 g/m3 water or chloramphenicol 0.5 g/m3 water.
Third, broodstock spawning and hatching
Macrobrachium rosenbergii broodstock was incubated at 25-26°C for about half a month, and spawning began to take place. At this time, broodstock should be batched in time to the spawning pool. Grab out for a special pool; In order to facilitate the larval rearing after fertilized eggs are hatched, the spawning shrimp can be picked up and placed in a prepared larval rearing tank (groove) for feeding until the larvae are hatched. The management during this period mainly ensures the various conditions required for the hatching of broodstock and fertilized eggs. The main tasks are as follows:
1. Regulation of water temperature and salt: The optimum water temperature for fertilized egg hatching of Macrobrachium rosenbergii is 26-28°C. It should be strictly ensured and the stability of the water temperature should be controlled during daily inflation and water exchange. The egg-holding shrimp is cultivated in fresh water. When the egg color changes from orange to gray (usually about 12 days after spawning), a small amount of seawater is added to the phase pool every day, so that the salinity gradually reaches 0.12-0.14%. When the larvae hatch out, they become suitable in salt water.
2. Feeding bait and controlling water quality: Egg-bearing shrimps still insist on feeding during the hatching period. Feed fresh fish and snail meat and other nutritious animal foods every day, and often suck waste contaminants. During the incubation period, aeration and oxygenation should be continuously carried out so that the water-soluble oxygen in the pool is near saturation.
Fourth, larval rearing
When larvae of Macrobrachium rosenbergii hatch out 1-2 days, broodstock should be caught in another broodstock pool for postpartum cultivating, and the zoea larvae should be incubated in a special pool.
1. Requirements for cultivation ponds and supporting facilities: The pools are generally cement pools, and the equipment to be equipped includes inflator pumps and supporting pipelines, and access to drainage pumps and generators. The juvenile larvae are mainly larvae of Inupulina larvae, so they also need cement tanks or plastic barrels for hatching.
2. Selection of seawater source and artificial seawater preparation method: The optimum daily salinity of the juvenile larvae is 0.012-0.014, so coastal sea-breeding can use natural seawater (no pollution) to mix brackish water with fresh water; if there is natural seawater Contamination, or nursery sites in inland areas, can be prepared with artificial seawater.
3, larvae density requirements: the density of larvae in the larval pool is generally 5-10 million per cubic meter of water, and a larval in a culturing pool requires hatching at the same time, otherwise different larvae mixed affect the survival rate, the general requirements of each Cubic rice can be bred to dilute shrimp seedlings from 2 to 40 thousand.
4. Feeding of bait: The newly hatched juvenile larvae begin to feed on their own yolk sac nutrition after the first molting. At this time, the feed that can be fed is mainly on the abundance of insects, and can also be fed. Cyanobacterial powder, yeast, light and cells, and rotifers; when the larvae have licked the skin 4 or 5 times, they can add cooked fish flesh pieces and egg yolks 3 times a day. Due to a large number of feeds, it is necessary to pay attention to the cleaning of the pool water. Every day, it is necessary to suck 2-3 times and exchange fresh water. When changing the water, pay special attention to the stability of the salinity and add fresh brackish water. As long as the food is sufficient, the oxygen is guaranteed to be inflated, the water temperature and salinity are properly controlled, and the larvae can be successfully metamorphosed into young prawns after 25-30 days of cultivation.
5. The larvae of the larvae must be adapted to the freshwater environment through the brackish water environment after the metamorphosis of juvenile shrimps, and finally they can only live in pure fresh water. The specific method is to gradually add fresh fresh water to the metamorphosis-complete larval rearing tank and reduce salinity. The desalination process is generally completed in one day. The desalted larval shrimp is raised for 3-4 days, and the temperature of the cultivation pond is adjusted to be similar to the temperature of the outside pool, so that it can be stocked or sold.
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