Crab artificial breeding is the key to the entire production process. Only by grasping this ring can we provide a large number of good quality crabs, laying the foundation for the entire breeding process. First, nursery preparatory work 1. Nursery pond scrub disinfection in the larvae before the discharge of 3 days to 5 days, the breeding pond should be thoroughly scrubbed and disinfected, the new nursery pond should also be soaked 1 month in advance, with a chlorine per cubic meter King "100 grams of Quanchiposa to disinfect, and then rinse with sterile seawater. (2) After the water-rejection of the residual water is eliminated, the disinfected seawater can be filtered and injected into use. 3. The live bait culture crab migratory larvae and big eye larvae are all omnivorous, especially active bait, and it is very important to cultivate the open bait. 1 Botanical live bait The live bourgeon commonly used in crab breeding is unicellular algae such as Phaeodactylum tricornutum, Platymonasaurus, Chlorella, among which chlorella is the best, but chlorella culture needs more. The human and material resources are not suitable for training. In order to solve this problem, “Yanyang†company selects foreign excellent algae species, uses modern biotechnology, and adopts advanced culture methods to produce pure natural Chlorella vulgaris powder and condensed chlorella fluid, which solves the problem during the seedling raising process. The opening bait problem. This concentrated chlorella liquid can be directly put into the nursery pond, and it can also be inoculated and expanded. After feeding, it was confirmed that the growth and development of zoea larvae can be promoted, and the survival rate can be significantly improved. 2 animal bait crab migratory larvae and big eye larvae like rotifers, Artemia, Cladocera, copepods and so on. Eggs can be hatched by hatching mature eggs, but the eggs of the eggs are the main ways of infection in the late juveniles. In order to cut off this route of transmission, they can be disinfected with "Cang'an 2". Sterilize and kill polyhelminths. Second, the cultivation of zoea juvenile zoea larvae mainly include artificial feeding, control of water temperature, aeration and oxygenation and strengthen management, prevention and control of pests and diseases. The molting development of the pods in different stages has different requirements on the environment and bait, especially in the first stage, because the food is passively fed, so the bait grain density fed in the nursery pond should be kept at 100,000 yuan per milliliter. More than one. At the same time, the prevention and control should be based on prevention and pest control. Third, desalination and out of the pool when the zoea larvae become desalinated larvae can be out of the pool, can be gradually added to the breeding pool by the "chloro-" disinfected fresh water, desalination time is about 4 days ~ 5 day. 1. The cultivation of crabs includes the entire growth and development of larval rearing crabs and young crabs. (1) Qingchi Disinfection: In order to completely kill the bacteria and enemy pests in the pool, they play the dual role of disinfection and clearing ponds. The water depth of 1 mu per mu is 15 days before the seedlings are lifted, and “Qingtang agent I†is used. 100ml Quanchiposa, kill wild fish and frogs, 3 days to 5 days after the use of 75 kg to 100 kg of lime per acre of crab ponds and "three generations of fish and shrimps" Quanchiposa, kill bacteria, adjust the PH value, Increase calcium ion content in water. (2) Create the environment: In the pool, plants such as black algae or planted water on the surface of the pond will be transplanted to create an environment conducive to habitat and even distribution of crab seedlings, reduce mutual killing, and perform good bait feeding work. (3) Feed cultivation: Crabs are omnivorous animals, especially animal feed. The cultivation of pool water not only requires high dissolved oxygen, but also must have a certain amount of leeches for feeding when the big eye larvae are under the pond. One week prior to planting, fertilization, fertilizer and water are added. The general application amount is 1 meter per acre, and 1 kg of urea is released. Add 2 kg superphosphate to culture plankton. During the cultivation period, fresh and palatable plant foods were fed and the remaining food was removed promptly. (4) Seed selection: The big eye larvae will be bred into crabs. The identification of seed quality is the key to the success of crab breeding. The selected quality standards are individual large, yellow-brown, shiny, and the ability to observe the swimming at natural water temperature is strong and free from disease. The water can be rapidly dried by hand-swiping dry water. The artificial breeding crab is 1 day before raising the seedling. When the salinity at 2 days had been reduced to 6 ç›, several crabs were kept in freshwater for a period of 24 hours or more. (5) Stocking of crabs: Before raining crabs, avoid as far as possible rainy and cold weather. After the long-distance transport of big-eyed larvae, sprinkle some water before putting the seedlings. After 10 minutes, put the crabs into the water and shake the grass. Let crabs swim freely. (6) Feed the big eye larvae to the first batch of juvenile crabs with the main biological feed in the pond, supplemented with 7:3 fish gizzards, and sprinkle the whole egg after filtering with a 10 mesh sieve. In the feeding method and feeding amount should be adhered to a small number of times, the number of feeding can be gradually reduced, in addition to the amount of feeding can also be adjusted with weather conditions and feeding conditions. 2. Problems and Countermeasures in the Breeding of Crab Breeds (1) The crabs and other crustaceans need to pass through the clamshell to grow. Each shell once seems to experience a life and death. Large-eyed larvae to juvenile crabs and metamorphosis growth because of their individual delicate, poor ability to adapt to the complex external environment, the performance is even more so. In particular, the germplasm resources of river crabs have been degraded in recent years, and their anti-stress ability is also poor, and the ecological environment of water bodies has been destroyed. Each time a shell has a large number of larvae can not normally complete metamorphosis and die. At the same time, due to the poor physical condition of the crabs, a large amount of chemical drugs cannot be used. Shanghai Fuyang Animal Pharmaceutical Co., Ltd.'s “Tseng Crab†solved this problem. The product uses pure Chinese medicine preparations, can effectively promote the normal oyster shell metamorphosis of large-eyed larvae and various stages of larvae, improve survival rate, and can prevent the emergence of early crab ashore. The field experiments in Tianjin and Shanghai proved that the survival rate of larval crabs can be significantly improved and the survival rate can reach more than 30%. It is recommended to promote the use. 2) Crab species Precocious Crab precocious puberty refers to the fact that some of the crab species produced in the current year are larger in size. Usually, the size of the crab is more than 20 grams. The gonads have developed and matured. High, brings more losses to farmers. In order to reduce this loss, the following measures should be adopted to reduce the proportion of precocious crabs: 1) Adopt local conditions, cast less animal food, and reasonably feed green feed. 2 The water depth is controlled from 1m to 1.2m, keeping the water fresh and changing the water in the hot season. 3 transplanting aquatic plants, the area of ​​aquatic plants should generally account for 1/3 or 1/4 of the crab pool. In this way, first, the aquatic plants can facilitate feeding and feeding of crabs, supplementing natural vitamins and nutrients. The second is that aquatic plants can purify water quality. The third is to provide a good habitat for crabs, which can be described as threefold. 4 The bait is mixed with “strong liver and gallbladder agent†to inhibit excessive nutrient conversion to gonads. IV. Artificial cultivation of adult crabs Artificial breeding of river crabs From the types of water areas that they use, there are ponds for raising crabs, rice fields for raising crabs, and lake cages for raising crabs. There are intensive culture and extensive culture from the farming methods. Take crab farming in rice fields as an example: 1. Selection and construction of field plots (1) Crab raising rice fields need to be close to excellent non-polluting water sources, drainage is convenient, clay soils are preferred as soil fertility, and field ridges are thicker than common ridges. (2) Construction: The main field projects for raising crabs in paddy fields include holding ponds, ring ditch and intra-trench ditch. The holding pool can be used to raise crab species or not. The ring ditch is mainly used as a place for crabs. The excavation was made along the ravine. The ravine was 3m to 5m in width and 1m to 1.5m in depth. Some cross ditches were excavated in the field. The ditches were 0.8m wide and 0.5m deep for the crabs to eat and hide. Tian Hao is widened and thickened, about 1 meter high. (2) Anti-escape facilities (1) The brick wall is used to prevent escape; ordinary bricks are used to build a wall about 0.5 meters high along the fields. The top layer protrudes inwards to prevent crabs from fleeing. (2) Plastic film can also be laid along the perimeter of the paddy field and supported by wood piles. 3. Drainage and Irrigation Facilities Drainage and irrigation channels may be specially laid, but original channels in paddy fields may also be used. However, gates must be installed at the entrance to the drainage area and sealed with nets to prevent the entry of enemy-damaged organisms and the escape of crabs. 4. Holding disinfection 2 months to 3 months of purchase of crab species for conservation, pool water use "chlor king" or "third generation fish shrimp security" for disinfection, crab species 20 ppm concentration of "complex furazolidone" soak 20 minutes after release Into the rice field for breeding. 5. Feeding and management During the breeding period, the water quality of the feedstuffs should be controlled and the disease and enemy harm should be prevented and eliminated. Fifth, the crab feeding the crab feeding from larvae to adult farming, different growth stages of the required nutrition is different, the intake of the bait is also different, the river crab jellyfish larvae can be selected as a phase one In the later period, the larvae and larvae are the main foods. Since the crabs have entered normal growth stage during the development of crabs and crabs, they need to ingest nutrient-rich substances, and the feeds fed in the actual breeding process are often difficult to achieve. This leads to the occurrence of nutritional deficiencies in crabs, resulting in slow growth and weakened resistance. It is therefore recommended to use "River Feed Additives". "River Crab Feed Additives" is based on the current status of domestic aquaculture using the latest scientific and technological achievements, and is supplemented with necessary nutrients for the growth of crabs. Balance feed nutrition, improve feed utilization, prevent nutrient diseases of river crabs, and increase disease resistance of river crabs. The growth of crabs is accomplished through the oyster shell, which increases the weight of the shell by about 20% once per pod. However, many crabs often die because the clam shells are not dead. This is in addition to the crab germplasm itself does not meet the local water environment, the factors related to the oyster shell and feed nutrients, water pH, pond water quality conditions are all related. "Prawns, Crabs, and Shell Extracts" use pure Chinese herbal preparations containing B, a dehulling hormone and yeast sterol, which are required for the growth and development of early animals. It is apparent that shrimp and crabs have periodic molting and lack of ecdysone resulting in crustacean insomnia. The curative effect is suggested to be fed with bait. One thing to note is that if the crabs are malnourished, that is, the peeling is not long. This reveals that in addition to adequate protein, mineral salts, and vitamins in the crab feed, pay attention to the proper combination of animal protein and vegetable protein, and add 10 per ton. Calcium dihydrogen phosphate, to meet the normal physiological growth requirements. VI. Prevention Techniques for Common Diseases of River Crabs The crabs have strong resistance to disease in the natural environment. However, in the case of high intensive breeding of ponds, the stocking density is high, the range of activities is limited, the water quality deteriorates, and the rearing and management methods are repeated. Defective, unbalanced feeding of food, etc., can easily lead to the occurrence of crab disease. At present, the main diseases that endanger the healthy breeding of crabs are the following: (1) The crab trembling disease (the crab shivering disease) The pathogen: It is initially considered to be a spherical virus. In the later period, aerobic bacteria such as Aeromonas hydrophila and other bacterial infections often become more serious. However, the lack of environmental factors and nutrient sources can also induce the occurrence of this disease. Symptoms: mainly foot trembling, supporting feet, claws to the ground or Shoulong, shrinking in the chest or hold into a group, the muscles of water, hemolymph liquid coagulation poor or not coagulation; when the secondary bacterial infection often have a large number of ascites, hepatoma Big and sick crabs stopped feeding and soon died. Epidemic situation: In 1994, the disease began to sporadically occur, and it has been widespread and widespread in the country. In recent years, it has become the most dangerous disease in crab breeding. Incidence: From 3 g to 250 g body weight will affect the crabs. Individuals weighing between 150 and 200 g will suffer from serious illnesses, from March to December in time, and from July to September in severe heat conditions. Rapid onset, high mortality, and severely affected crab ponds, even no harvest. When ciliate parasites occur on the crab body, the disease is more prone to outbreak and the condition is more severe than normal. Control methods: 1. If there is an immobilized ciliate parasite on the crab body, first kill the ectoparasite with “Crabâ€. 2. Quanchiposa disinfectant "three generations of fish and shrimp" will kill viruses and bacteria in the water. The number of antiseptics poured out depends on the severity of the disease. Generally, it should be splashed once every 10 days. The dosage is 0.3ppm. 3. Add 1 kilogram of "Cang'an 3" per 100 kg of feed, make granules for medicine and feeding, once in the morning and at night, and even feed 7 days for one course of treatment; when the condition is particularly serious, you can feed for one week. The specific number of days for feeding the medicine depends on the condition of the disease. Generally, the crabs are fed and fed for 1 to 2 days after they have died. The use of "Cang'an No. 3" in conjunction with the use of crab feed additives produced by Shanghai Xiangyang Animal Pharmaceutical Co., Ltd. will have better results. 4. After the disease is cured, Quanchipa is splashed with lime and the water is made alkaline. Treatment Precautions: 1. If the crab body surface has fixed ciliate parasitism, it must be killed first, otherwise it will seriously affect the curative effect, and it is easy to re-infect the disease (due to parasite damage to the crab shell and crest). 2. The use of external disinfectants and internal medicine baits must be combined to kill all viruses and bacteria in the body of water and crabs in order to cure the disease. 3 splashing disinfectant to Quanchiposa, can not only spill the local, and the number of spills should increase with the severity of the disease. 4. Feed the bait to ensure that the sick crab that can still eat can eat enough doses. (1) It should be treated as soon as possible. If a seriously ill crab has lost its appetite, it cannot be cured. (2) The bait should be mixed evenly to make a bait with good stability in water. (3) The amount of medicine to be fed should be appropriate. (4) The bait should be scattered and sprinkled. (5) The bait should be eaten at least for 7 days or stopped for death and then fed for 1 to 2 days. Do not stop the medicine prematurely. 5. Diseased crabs should be buried in a timely manner and not thrown everywhere. After the cure, prevention work should still be done because crabs do not produce life-long immunity to the disease. (b) The pathogen of river crab ascites: Aeromonas hydrophila, malnutrition, and non-sterile food. Symptoms: The diseased crab is unresponsive, the appetite is reduced or not eaten, there is a lot of ascites in the abdomen, the heart is swollen, and the heart beats. Treatment: 1. Proportional feeding "Crab ascites elimination." 2. Add crab feed additives to the feed. (c) Crab brown spot (crustacean disease) Pathogen: Vibrio parahaemolyticus. Symptoms: Diseased crabs have brown, reddish-brown, spotted lesions on the carapace of the crabs. In severe cases, the spots develop into massive masses, with ulcers at the center and black edges, which in turn cause other bacteria or fungi to invade and seriously affect the growth of crabs. Treatment: External use of "bromochlorohydantoin" 0.3ppm, Quanchiposa. (d) black shank pathogens: the deterioration of environmental conditions, promote the proliferation of harmful bacteria, resulting in the incidence of river crab infections. Symptoms: Diseased crabs appear dark gray or black, breathing difficulties, slow action, gradually leading to death. Treatment: 1. "Cang An 2" Quanchiposa. 2. The crabs were soaked in a 5 ppm solution of furazolidone for 2 minutes to 3 minutes. 3. For each 100 kg of bait, compound furazolidone "100 g, stirring uniformly made into bait feeding. Appropriate increase in the amount of serious illness. (E) fixed ciliate disease pathogen: Reproductive worms, bell shaped insects, poly insects Ciliated worms, etc. Symptoms: When there is a small amount of parasites, they cannot be seen with the naked eye and must be examined with a microscope. When the condition is serious, there are many villous substances on the body surface of the crab, the body surface is dirty, and the diseased crab is slow to move. Treatment: 1 meter deep water per mu, use 1000 grams of "crab safe", fully dissolve the drug with warm water, splash evenly in the whole pool. If there are still a few residual worms, you can splash it once in about ten days after treatment. Can be completely cured.(6) Causes of ecchymansis: malnutrition or environmental deterioration Symptoms: There is a gap between the posterior edge of abdomen and abdominal abdomen of the crab head, but the old shell cannot be removed. Blackening, and eventually death.Treatment: 200 grams of shrimp and crab dehulled food per 100 kilograms of bait, mixed evenly, made into granular bait, once a day, even fed 10 days.Preventive measures: 1. Crab pool regularly spilled stone , Adjust the water quality to supplement calcium 2. Add "River crab feed additive" to the feed to supplement the crab nutrition 3. Crab pond regularly uses 0.3ppm of "Cang'an 2", splashing at Quanchipue 4. Keeping the crab pond environment quiet 5. Do not buy precocious young crabs.
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