By referring to the achievements of shrimp disease prevention and control at home and abroad and combining with the current conditions of shrimp farming in Shenzhen, we have calculated the method of low-salinity and disease-prevention farming for tiger prawns.
The main technical point of this method is: “Semi-closed†means to change the traditional method of large-scale irrigation in the past. After 60 days or so, the water with good quality is added only in the tidal period every day, and 1-2 ppm is used immediately after adding the seawater. The strong disinfecting spirit disinfects the whole water body. The entire aquaculture process is basically undrained, which cuts off the pathogens that damage the pathogens of P. monodon along with the seawater. "Low salinity" means that seawater salinity is about 30% at the initial stage of seedling release. Then, a small amount of freshwater is added every day and the salinity is gradually reduced until about 10% before the harvest.
Due to the low salinity, the spread of virulent vibrio that can multiply in high salinity environments can be suppressed, thereby reducing the chances of a large number of deaths due to outbreaks of mixed shrimp farming. In addition to the above two measures, the "prevention and cultivation method" also applies appropriate amounts of quicklime to regulate water quality throughout the breeding process. On the one hand, the PH value is gradually increased from about 8.l at the time of seedling investment to about 8.9 to create the optimum pH environment during the growth of Penaeus monodon; on the other hand, it also promotes the purification of cultured water to enable the cultivation of shrimp. Normal growth and development, enhance the body resistance to disease, and in the late aquaculture plus fresh live bait, the first use of 20ppm powerful disinfection soak disinfection, in order to reduce the opportunity for pathogens with fresh live bait. Integrate the above measures to achieve the effect of disease prevention.
From 1994 to 1995, we set up trials at the Kwai Chung Dam light shrimp farm in Shenzhen. We conducted a three-phase (three) breeding trial in two years. The breeding area was 223 mu (excluding the control group), and the survival rate was over 50%. The average yield is more than 100 kg. On November 3, 1995, it was approved by the Shenzhen Science and Technology Bureau (Shenzhen Kamma No. 06 of 1995).
In 1996, the results were promoted in six distribution sites in Shenzhen, Shenzhen, Raoping City, Shanwei City, Haifeng County, Huidong County, and Dianbai County, with an acreage of 828 mu. The aquaculture production at the 6 points was significantly higher than that in 1994 and 1995. The average yield per mu of the whole farm was 183.15 kg in Kwai Chung, Okushima, Shenzhen and 238.9 kg in the highest single pond.
First, the test situation
The first phase of the experiment was conducted at Kwai Chung Dam Light Shrimp Farm in Shenzhen from April to July 1994. It consists of 5 pools totalling 60 mu of cultured water. One of the three test pool area of ​​38 acres, 2 control pool area of ​​22 acres. The seedlings were planted in mid-April, and the control ponds used the traditional culture method (big row irrigation). The test pool adopts the "half-closed, low-salinity" disease prevention culture method. The control pond is raised to the onset of the disease in early May. By May 16, the two pools of shrimps all died. There was no yield, and there was no disease in the test pool. On July 19th (cultured for 93 days), the Municipal Bureau of Agriculture presided over the on-site assessment of experts from the South China Sea Fisheries Research Institute and the Institute of Hydrobiology, Chinese Academy of Sciences. The survival rate was over 50%. The shrimps were healthy and the average body length was 12.0 cm. The average yield was 84.4. Kg, the maximum yield of 88.7 kg per mu. The second phase of the experiment was from April to early August 1995. The test pool is also located at Kwai Chung Dam Light Shrimp Farm. This time it has expanded to 18 shrimp ponds with a total area of ​​185 mu.
"Semi-enclosed, low salinity" measures are the same as in the first period. However, in order to overcome the shortcomings of the lean body light of the shrimp in 1994, improvements were made in two aspects: first, the strict freshly sterilized raw material was fed; secondly, clean seawater was appropriately added in the late tidal period and used after seawater addition. A certain amount of disinfection spirit is used to disinfect the whole water body. Cultured for 93 days, presided over by the Shenzhen Municipal Bureau of Science and Technology. On-site trial fishing (netting), the arrested shrimp is very healthy, with an average body length of 10.0 cm and a maximum length of 18.0 cm, with 90 tails per kilogram, a survival rate of 60%, an average yield of 118.5 kg per mu, and a maximum yield of 139 kg per mu. All shrimp farms in the same area have died of varying degrees of disease. Half of the shrimp ponds are even out of production. The average yield of the shrimp farm that has not been produced is only about 25-30 kg. The third phase of repeated trials was carried out on August 25, 1995 to March 3, 1995 at Baguang Azizi Shrimp Farm. The two trial ponds had a total area of ​​23 mu, with a seedling density of 13300 mu per mu. Seedlings were sampled and gi.8% of shrimps were infected with virus inclusion bodies. After 62 days of aquaculture, the percentage of shrimp inclusion virus inclusion bodies was 55.0%, which was 36.8% less than the first test before the seedlings were released. On November 3, 71 days after the breeding, the Shenzhen Science and Technology Bureau presided over the site acceptance of 2 In the test pool, shrimp was very healthy, with an average body length of 10.2 centimeters, 88 fishes per kilogram, 2104.5 kilograms of total shrimp production, a survival rate of 60.5%, and an average yield of gi.75% kilograms. The five control ponds of the same batch of shrimp seedlings used in the same shrimp farms in the same sea area were gradually diseased after 50 days, and there were 3 pools of dead light when the knife was cut.
Second, discussion and suggestions
1. Semi-closed, low-salinity, disease-resistance culture methods Cultured giant prawn is to improve the aquaculture environment to prevent the occurrence of shrimp diseases. In addition to the addition of clean seawater in the tidal period, the whole pond water body is used after the rearing period. Disinfection and injection of fresh live feed before using a strong disinfectant to disinfect the body through the disinfection of pathogens to reduce the aquaculture water, with semi-enclosed, low salinity and appropriate amount of lime control is also a measure to reduce water pathogens. At the same time, the optimum growth environment for P. monodon from the seedling stage to the growth stage of shrimp was also established, and the ability to resist disease was enhanced to achieve a large number of deaths caused by outbreak shrimp disease during the whole breeding process.
2. The culture method can not only prevent disease, increase the survival rate, increase the output, but also save the production expenses (including the saving of electrician, labor, feed, etc. to improve the production efficiency).
3. The results should still be implemented in strict clear ponds, exposure, poison pool, buy seedlings, reasonable density, adequate feed, do not abuse drugs and other effective measures.
4. Whether or not the shrimp pond leaks will have a great impact on semi-closed farming. Pool water or seawater leakage will affect the formation of a good body of water. When promoting this result, strict precautions should be taken to prevent leakage.
5. Physical and chemical factors of water quality: During the whole breeding process, dissolved oxygen in the water body should be kept at 5.0 mg or more, ammonia nitrogen should be controlled at 0.25 mg or less, pH value should be controlled between 8.0 and 8.9, and salinity should be changed from high to low. More than 3%, finally control at 10%.
The main technical point of this method is: “Semi-closed†means to change the traditional method of large-scale irrigation in the past. After 60 days or so, the water with good quality is added only in the tidal period every day, and 1-2 ppm is used immediately after adding the seawater. The strong disinfecting spirit disinfects the whole water body. The entire aquaculture process is basically undrained, which cuts off the pathogens that damage the pathogens of P. monodon along with the seawater. "Low salinity" means that seawater salinity is about 30% at the initial stage of seedling release. Then, a small amount of freshwater is added every day and the salinity is gradually reduced until about 10% before the harvest.
Due to the low salinity, the spread of virulent vibrio that can multiply in high salinity environments can be suppressed, thereby reducing the chances of a large number of deaths due to outbreaks of mixed shrimp farming. In addition to the above two measures, the "prevention and cultivation method" also applies appropriate amounts of quicklime to regulate water quality throughout the breeding process. On the one hand, the PH value is gradually increased from about 8.l at the time of seedling investment to about 8.9 to create the optimum pH environment during the growth of Penaeus monodon; on the other hand, it also promotes the purification of cultured water to enable the cultivation of shrimp. Normal growth and development, enhance the body resistance to disease, and in the late aquaculture plus fresh live bait, the first use of 20ppm powerful disinfection soak disinfection, in order to reduce the opportunity for pathogens with fresh live bait. Integrate the above measures to achieve the effect of disease prevention.
From 1994 to 1995, we set up trials at the Kwai Chung Dam light shrimp farm in Shenzhen. We conducted a three-phase (three) breeding trial in two years. The breeding area was 223 mu (excluding the control group), and the survival rate was over 50%. The average yield is more than 100 kg. On November 3, 1995, it was approved by the Shenzhen Science and Technology Bureau (Shenzhen Kamma No. 06 of 1995).
In 1996, the results were promoted in six distribution sites in Shenzhen, Shenzhen, Raoping City, Shanwei City, Haifeng County, Huidong County, and Dianbai County, with an acreage of 828 mu. The aquaculture production at the 6 points was significantly higher than that in 1994 and 1995. The average yield per mu of the whole farm was 183.15 kg in Kwai Chung, Okushima, Shenzhen and 238.9 kg in the highest single pond.
First, the test situation
The first phase of the experiment was conducted at Kwai Chung Dam Light Shrimp Farm in Shenzhen from April to July 1994. It consists of 5 pools totalling 60 mu of cultured water. One of the three test pool area of ​​38 acres, 2 control pool area of ​​22 acres. The seedlings were planted in mid-April, and the control ponds used the traditional culture method (big row irrigation). The test pool adopts the "half-closed, low-salinity" disease prevention culture method. The control pond is raised to the onset of the disease in early May. By May 16, the two pools of shrimps all died. There was no yield, and there was no disease in the test pool. On July 19th (cultured for 93 days), the Municipal Bureau of Agriculture presided over the on-site assessment of experts from the South China Sea Fisheries Research Institute and the Institute of Hydrobiology, Chinese Academy of Sciences. The survival rate was over 50%. The shrimps were healthy and the average body length was 12.0 cm. The average yield was 84.4. Kg, the maximum yield of 88.7 kg per mu. The second phase of the experiment was from April to early August 1995. The test pool is also located at Kwai Chung Dam Light Shrimp Farm. This time it has expanded to 18 shrimp ponds with a total area of ​​185 mu.
"Semi-enclosed, low salinity" measures are the same as in the first period. However, in order to overcome the shortcomings of the lean body light of the shrimp in 1994, improvements were made in two aspects: first, the strict freshly sterilized raw material was fed; secondly, clean seawater was appropriately added in the late tidal period and used after seawater addition. A certain amount of disinfection spirit is used to disinfect the whole water body. Cultured for 93 days, presided over by the Shenzhen Municipal Bureau of Science and Technology. On-site trial fishing (netting), the arrested shrimp is very healthy, with an average body length of 10.0 cm and a maximum length of 18.0 cm, with 90 tails per kilogram, a survival rate of 60%, an average yield of 118.5 kg per mu, and a maximum yield of 139 kg per mu. All shrimp farms in the same area have died of varying degrees of disease. Half of the shrimp ponds are even out of production. The average yield of the shrimp farm that has not been produced is only about 25-30 kg. The third phase of repeated trials was carried out on August 25, 1995 to March 3, 1995 at Baguang Azizi Shrimp Farm. The two trial ponds had a total area of ​​23 mu, with a seedling density of 13300 mu per mu. Seedlings were sampled and gi.8% of shrimps were infected with virus inclusion bodies. After 62 days of aquaculture, the percentage of shrimp inclusion virus inclusion bodies was 55.0%, which was 36.8% less than the first test before the seedlings were released. On November 3, 71 days after the breeding, the Shenzhen Science and Technology Bureau presided over the site acceptance of 2 In the test pool, shrimp was very healthy, with an average body length of 10.2 centimeters, 88 fishes per kilogram, 2104.5 kilograms of total shrimp production, a survival rate of 60.5%, and an average yield of gi.75% kilograms. The five control ponds of the same batch of shrimp seedlings used in the same shrimp farms in the same sea area were gradually diseased after 50 days, and there were 3 pools of dead light when the knife was cut.
Second, discussion and suggestions
1. Semi-closed, low-salinity, disease-resistance culture methods Cultured giant prawn is to improve the aquaculture environment to prevent the occurrence of shrimp diseases. In addition to the addition of clean seawater in the tidal period, the whole pond water body is used after the rearing period. Disinfection and injection of fresh live feed before using a strong disinfectant to disinfect the body through the disinfection of pathogens to reduce the aquaculture water, with semi-enclosed, low salinity and appropriate amount of lime control is also a measure to reduce water pathogens. At the same time, the optimum growth environment for P. monodon from the seedling stage to the growth stage of shrimp was also established, and the ability to resist disease was enhanced to achieve a large number of deaths caused by outbreak shrimp disease during the whole breeding process.
2. The culture method can not only prevent disease, increase the survival rate, increase the output, but also save the production expenses (including the saving of electrician, labor, feed, etc. to improve the production efficiency).
3. The results should still be implemented in strict clear ponds, exposure, poison pool, buy seedlings, reasonable density, adequate feed, do not abuse drugs and other effective measures.
4. Whether or not the shrimp pond leaks will have a great impact on semi-closed farming. Pool water or seawater leakage will affect the formation of a good body of water. When promoting this result, strict precautions should be taken to prevent leakage.
5. Physical and chemical factors of water quality: During the whole breeding process, dissolved oxygen in the water body should be kept at 5.0 mg or more, ammonia nitrogen should be controlled at 0.25 mg or less, pH value should be controlled between 8.0 and 8.9, and salinity should be changed from high to low. More than 3%, finally control at 10%.
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