Penaeus vannamei (hereinafter referred to as white prawn) is a hot spot in the aquaculture industry this year. However, with the expansion of white shrimp aquaculture areas, the disease situation has become more and more common. How to raise white shrimps healthily is the most concern for shrimp farmers. topic.
To grasp the poor quality of shrimp seedlings and the low survival rate, how can we ensure the success of breeding? Some shrimp farmers only consider the price when buying seedlings, but they do not pay attention to the quality of shrimp seedlings. Some shrimp farmers know that the quality of shrimp seedlings is poor, but there are chances that they can be solved by increasing the number of shrimp seedlings. Poor quality and low survival rate. There are countless numbers of shrimp in ponds. It is easy to grow alive.
It is recommended that you pay attention to the quality when purchasing seedlings, and it is best to purchase SPF (no specific pathogen) shrimp seedlings, but this is not easy because of the low number of SPF shrimp seedlings. Generally, when purchasing seedlings, the size is larger, the average body length is longer than 1 cm, and the vibrancy is strong. If you use your fingers to startle it, you can bounce and evade, or you can stir the water flow to quickly move over and swim backwards. Special attention should be paid to not buying fast desalination. (The salinity drops by more than 2 per day).
It is one of the most important issues for shrimp farmers to raise seedling density under reasonable seedling density. How much density can we take into consideration both in terms of yield, prevent diseases, and reduce the risk of breeding? In order to pursue high yields, some shrimp farmers have more than 100,000 seedlings per acre. As a result, shrimps are not dead due to lack of oxygen, they are infectious diseases, and they suffer heavy losses.
It is suggested that the seedling density must be determined according to the actual situation of the pond. Under normal circumstances, a pond with a depth of 13 to 14 meters can be planted with 30,000 to 350,000 animals per acre; a pond at a level of 15 to 16 meters can be planted at a ratio of 350,000 to 40,000 per acre; and a pond of 17 to 18 meters can be used. Mu can be 40,000-50,000, and ponds over 18 meters in size should not exceed 60,000 per mu. And to be equipped with enough aerators, an aerator every 2-25 acres, as well as the corresponding standby power (generator), to prevent problems due to lack of oxygen in the late culture.
The practice of first applying fertilizer and then down seedlings showed that the white shrimp seedlings in the lower pool mainly depended on plankton in drinking water. Before the shrimp grows in the pool, it is necessary to make water first so that the shrimp can have enough food after going down the pool. Fertilizer can be used organic fertilizer with some inorganic fertilizer (fertilizer), or directly with some special aquatic fertilizer, but these methods will increase the ammonia in the pool water, affect the disease resistance and survival rate of shrimp seedlings.
It is recommended to use rice bran (15-20 kg per acre), photosynthetic bacteria (4-5 kg ​​per acre), and fishmeal (25-5 kg ​​per acre) to add water and dip for 12-24 hours before Quanchiposa. If the bottom of the pool is more fat, you can reduce the amount; if the bottom is too thin, you can add some more fertilizer. After 2 to 3 days, you can get the ideal fertilizer and water effect. Due to the use of photosynthetic bacteria in fertilizers and water, it can effectively absorb ammonia produced during the process of fertilizer and water and prevent deterioration of water quality. After the shrimp grows into the pool, when the transparency of the water body is greater than 50 cm, fertilizer and water must be promptly provided to prevent the number of plankton from drastically decreasing. It is then very difficult to fertilize the water quality.
Timely seedlings When the shrimp seedlings grow to 2-3 cm in length, the plankton in the pool water can hardly meet the feeding needs of the shrimp seedlings. If nutrition is not added in time, the shrimp seedlings will grow thin and resistant to disease. Extremely poor power will also affect the survival rate.
At this time, it is recommended that we take timely measures to supplement high-nutrient substances, such as adding fish and shrimp Zhuangyuan (also known as antiviral yuan, a high protein feed), immune polysaccharides, and multivitamins to the feed. Robust, disease-resistant, lays the foundation for successful breeding.
Scientific Feeding Feed Feeding is one of the most difficult techniques to control in white shrimp aquaculture. Too much material will destroy the sediment and water quality; too little material will affect the healthy growth of shrimp. Even if the daily feeding amount is accurate, the proportion and time for feeding each meal in the whole day must be reasonable and scientific, so as to ensure the healthy growth of the shrimp, reduce the feed coefficient, and reduce the production cost.
It is suggested that in the high water temperature period (25°C-35°C), the reasonable feeding is four meals a day, the ratio of each meal is 25:15:4:2, and the time is 6-7 hours, 12-13 hours, 18 - 19:00, 22:23. In the water temperature period (18°C-24°C) suitable for the growth of white shrimp, reasonable feeding is three meals a day at a ratio of 2:3:5, and the time is 7-8 hours, 12-13 hours, 18- At 19:00, because of the cooler weather at this time, especially late at night and early morning, breakfast was less, and late night shrimp did not eat, so there was no need to feed. In addition, one or two nets of about 1 square meters should be set up to check the eating and drinking of shrimp. Under normal circumstances, after each meal is fed to the finished diet, about 1% of the feed is fed into the nets, checked every 15 minutes, and eaten well from 1 to 15 hours. If you eat too much time, cut your feed; if you eat too little, add more. Especially in the middle and late breeding period, the water quality becomes very fat due to the increase in the amount of feeds and the accumulation of excrement. At this time, it is necessary to control the material and reduce the feed, feed 60% to 70% of the normal feed, and force the shrimp to feed the bottom of the pool. Some of the organic matter will gradually be fed to normal when the fertility of the pool declines. This will prevent deterioration of sediment and water quality and ensure the smooth growth of the shrimp.
Eco-environment microbial preparations include liquid photosynthetic bacteria and solid powder dormant bacteria. During the culture of white shrimp, microbial preparations are used in the whole process, which can reduce the ammonia nitrogen produced by fermentation of the leftovers and shrimp excrement and purify the water. Shrimp creates a good living environment and promotes the healthy growth of shrimp.
It is recommended that due to the large amount of excretion of shrimp during the later period of cultivation, the amount of use should be increased to achieve the desired effect. At the same time, you can also use 2% -3% of liquid photosynthetic bacteria or 1% of powder dormant bacteria mix feed, adjust the shrimp's stomach, so that the shrimp to maintain a strong appetite, thus promoting growth, shorten the breeding cycle.
When the white shrimp grows to a body length of about 5 cm, 5 to 10 squid (250-500 g) are added per mu, and 15 squid (species of the same size as squid) are used per mu to stabilize the water quality through biological means. . Because squid likes to filter certain algae in the water, it can prevent overgrowth of algae, stabilize the algae phase and prevent pH from drastic change; Squid likes to feed the bottom of the pool of organic matter (including leftovers and shrimp excrement), can prevent bottom Quality and water quality deteriorate.
Timely dilution shows that white shrimp grows faster in low-salinity water and has a higher probability of catching virus disease in salinity water. Therefore, when the shrimp grows to a body length of 3-5 cm, it can gradually add water and reduce it. The salinity of water. However, due to the thin shell of white prawns, which is sensitive to changes in water quality, the stress response is very strong. If too much water is added in a single amount, the shrimp will not be properly shelled and the shrimp disease resistance will be reduced. Therefore, the amount of added water should be appropriate. .
It is recommended that, in general, the first addition amount should not exceed 5% of the water depth, and gradually increase until later, and the maximum addition amount can reach about 25% of the water depth. In the later stage of cultivation, the water quality may become poor due to the accumulation of organic matter in the water. Adding new water at this time will help improve the water quality, reduce the concentration of bacteria and viruses in the water, prevent the occurrence of diseases, and promote the health of shrimp.
It is recommended that from the middle of aquaculture, attention should be paid to regular microscopic examinations, especially to the abdominal foot (swimming foot) and temporal tissue. When the ciliate of the gastropod reaches a high density (in 1010 microscope, the number of ciliates in a field is called high density in more than 40 grains), it can cause white shrimps to reduce their feeding and not to shell; Caterpillar reaches medium and high density (about 30 or more grains). When the dissolved oxygen is low in bad weather, it can directly cause the shrimp to suffocate and die. Prevent fibrids from killing the second generation and prevent it once every 15 days. Pest control should be careful not to use irritating drugs such as copper sulphate or zinc sulphate, or you may lose out. If the ciliate is not very serious, it can also be gradually reduced by adjusting the water quality so that the ciliate lacks nutrition and achieves the purpose of prevention.
Dissolved oxygen should ensure that white shrimps have strong countercurrent habits. Therefore, when setting up aerators, besides rotating aerators in the middle of the pool, add waterwheels to the poolside (about 3 meters offshore). The oxygen aerator makes the pool water form a micro-flowing water environment, which allows the shrimp to exercise more, speed up the metabolism, strengthen the constitution and increase the resistance to disease. It is necessary to diligently open the aerator so that the water in the pool can maintain high dissolved oxygen. This will not only promote the appetite and disease resistance of the shrimp, but also reduce the toxicity of ammonia, nitrite, hydrogen sulfide, and other toxic substances, so that the shrimp can maintain Strong vitality.
In addition, with the expansion of the aquaculture area and the increase in the number of seedlings, the original germplasm advantage of white shrimp is gradually weakening. At present, the white prawn virus disease (especially white spot syndrome) has become more common, and it is necessary to make the white prawn grow healthily. , but also regularly disinfect the body of water and internal medicine baits to prevent the occurrence of disease; regular testing of water quality indicators, to master the changes in water quality, prevent water quality deterioration. It is worth mentioning that there is information that the protein demand of white prawns on feed can be very low, and it turns out that this statement is not correct. If low-protein diet is fed, the white prawns will have very weak constitution and disease resistance. Poor, the breeding cycle is also longer, increasing the feed coefficient and production costs. Therefore, to ensure the healthy growth and stable yield of white shrimp, feed should be fed with more nutritious.
To grasp the poor quality of shrimp seedlings and the low survival rate, how can we ensure the success of breeding? Some shrimp farmers only consider the price when buying seedlings, but they do not pay attention to the quality of shrimp seedlings. Some shrimp farmers know that the quality of shrimp seedlings is poor, but there are chances that they can be solved by increasing the number of shrimp seedlings. Poor quality and low survival rate. There are countless numbers of shrimp in ponds. It is easy to grow alive.
It is recommended that you pay attention to the quality when purchasing seedlings, and it is best to purchase SPF (no specific pathogen) shrimp seedlings, but this is not easy because of the low number of SPF shrimp seedlings. Generally, when purchasing seedlings, the size is larger, the average body length is longer than 1 cm, and the vibrancy is strong. If you use your fingers to startle it, you can bounce and evade, or you can stir the water flow to quickly move over and swim backwards. Special attention should be paid to not buying fast desalination. (The salinity drops by more than 2 per day).
It is one of the most important issues for shrimp farmers to raise seedling density under reasonable seedling density. How much density can we take into consideration both in terms of yield, prevent diseases, and reduce the risk of breeding? In order to pursue high yields, some shrimp farmers have more than 100,000 seedlings per acre. As a result, shrimps are not dead due to lack of oxygen, they are infectious diseases, and they suffer heavy losses.
It is suggested that the seedling density must be determined according to the actual situation of the pond. Under normal circumstances, a pond with a depth of 13 to 14 meters can be planted with 30,000 to 350,000 animals per acre; a pond at a level of 15 to 16 meters can be planted at a ratio of 350,000 to 40,000 per acre; and a pond of 17 to 18 meters can be used. Mu can be 40,000-50,000, and ponds over 18 meters in size should not exceed 60,000 per mu. And to be equipped with enough aerators, an aerator every 2-25 acres, as well as the corresponding standby power (generator), to prevent problems due to lack of oxygen in the late culture.
The practice of first applying fertilizer and then down seedlings showed that the white shrimp seedlings in the lower pool mainly depended on plankton in drinking water. Before the shrimp grows in the pool, it is necessary to make water first so that the shrimp can have enough food after going down the pool. Fertilizer can be used organic fertilizer with some inorganic fertilizer (fertilizer), or directly with some special aquatic fertilizer, but these methods will increase the ammonia in the pool water, affect the disease resistance and survival rate of shrimp seedlings.
It is recommended to use rice bran (15-20 kg per acre), photosynthetic bacteria (4-5 kg ​​per acre), and fishmeal (25-5 kg ​​per acre) to add water and dip for 12-24 hours before Quanchiposa. If the bottom of the pool is more fat, you can reduce the amount; if the bottom is too thin, you can add some more fertilizer. After 2 to 3 days, you can get the ideal fertilizer and water effect. Due to the use of photosynthetic bacteria in fertilizers and water, it can effectively absorb ammonia produced during the process of fertilizer and water and prevent deterioration of water quality. After the shrimp grows into the pool, when the transparency of the water body is greater than 50 cm, fertilizer and water must be promptly provided to prevent the number of plankton from drastically decreasing. It is then very difficult to fertilize the water quality.
Timely seedlings When the shrimp seedlings grow to 2-3 cm in length, the plankton in the pool water can hardly meet the feeding needs of the shrimp seedlings. If nutrition is not added in time, the shrimp seedlings will grow thin and resistant to disease. Extremely poor power will also affect the survival rate.
At this time, it is recommended that we take timely measures to supplement high-nutrient substances, such as adding fish and shrimp Zhuangyuan (also known as antiviral yuan, a high protein feed), immune polysaccharides, and multivitamins to the feed. Robust, disease-resistant, lays the foundation for successful breeding.
Scientific Feeding Feed Feeding is one of the most difficult techniques to control in white shrimp aquaculture. Too much material will destroy the sediment and water quality; too little material will affect the healthy growth of shrimp. Even if the daily feeding amount is accurate, the proportion and time for feeding each meal in the whole day must be reasonable and scientific, so as to ensure the healthy growth of the shrimp, reduce the feed coefficient, and reduce the production cost.
It is suggested that in the high water temperature period (25°C-35°C), the reasonable feeding is four meals a day, the ratio of each meal is 25:15:4:2, and the time is 6-7 hours, 12-13 hours, 18 - 19:00, 22:23. In the water temperature period (18°C-24°C) suitable for the growth of white shrimp, reasonable feeding is three meals a day at a ratio of 2:3:5, and the time is 7-8 hours, 12-13 hours, 18- At 19:00, because of the cooler weather at this time, especially late at night and early morning, breakfast was less, and late night shrimp did not eat, so there was no need to feed. In addition, one or two nets of about 1 square meters should be set up to check the eating and drinking of shrimp. Under normal circumstances, after each meal is fed to the finished diet, about 1% of the feed is fed into the nets, checked every 15 minutes, and eaten well from 1 to 15 hours. If you eat too much time, cut your feed; if you eat too little, add more. Especially in the middle and late breeding period, the water quality becomes very fat due to the increase in the amount of feeds and the accumulation of excrement. At this time, it is necessary to control the material and reduce the feed, feed 60% to 70% of the normal feed, and force the shrimp to feed the bottom of the pool. Some of the organic matter will gradually be fed to normal when the fertility of the pool declines. This will prevent deterioration of sediment and water quality and ensure the smooth growth of the shrimp.
Eco-environment microbial preparations include liquid photosynthetic bacteria and solid powder dormant bacteria. During the culture of white shrimp, microbial preparations are used in the whole process, which can reduce the ammonia nitrogen produced by fermentation of the leftovers and shrimp excrement and purify the water. Shrimp creates a good living environment and promotes the healthy growth of shrimp.
It is recommended that due to the large amount of excretion of shrimp during the later period of cultivation, the amount of use should be increased to achieve the desired effect. At the same time, you can also use 2% -3% of liquid photosynthetic bacteria or 1% of powder dormant bacteria mix feed, adjust the shrimp's stomach, so that the shrimp to maintain a strong appetite, thus promoting growth, shorten the breeding cycle.
When the white shrimp grows to a body length of about 5 cm, 5 to 10 squid (250-500 g) are added per mu, and 15 squid (species of the same size as squid) are used per mu to stabilize the water quality through biological means. . Because squid likes to filter certain algae in the water, it can prevent overgrowth of algae, stabilize the algae phase and prevent pH from drastic change; Squid likes to feed the bottom of the pool of organic matter (including leftovers and shrimp excrement), can prevent bottom Quality and water quality deteriorate.
Timely dilution shows that white shrimp grows faster in low-salinity water and has a higher probability of catching virus disease in salinity water. Therefore, when the shrimp grows to a body length of 3-5 cm, it can gradually add water and reduce it. The salinity of water. However, due to the thin shell of white prawns, which is sensitive to changes in water quality, the stress response is very strong. If too much water is added in a single amount, the shrimp will not be properly shelled and the shrimp disease resistance will be reduced. Therefore, the amount of added water should be appropriate. .
It is recommended that, in general, the first addition amount should not exceed 5% of the water depth, and gradually increase until later, and the maximum addition amount can reach about 25% of the water depth. In the later stage of cultivation, the water quality may become poor due to the accumulation of organic matter in the water. Adding new water at this time will help improve the water quality, reduce the concentration of bacteria and viruses in the water, prevent the occurrence of diseases, and promote the health of shrimp.
It is recommended that from the middle of aquaculture, attention should be paid to regular microscopic examinations, especially to the abdominal foot (swimming foot) and temporal tissue. When the ciliate of the gastropod reaches a high density (in 1010 microscope, the number of ciliates in a field is called high density in more than 40 grains), it can cause white shrimps to reduce their feeding and not to shell; Caterpillar reaches medium and high density (about 30 or more grains). When the dissolved oxygen is low in bad weather, it can directly cause the shrimp to suffocate and die. Prevent fibrids from killing the second generation and prevent it once every 15 days. Pest control should be careful not to use irritating drugs such as copper sulphate or zinc sulphate, or you may lose out. If the ciliate is not very serious, it can also be gradually reduced by adjusting the water quality so that the ciliate lacks nutrition and achieves the purpose of prevention.
Dissolved oxygen should ensure that white shrimps have strong countercurrent habits. Therefore, when setting up aerators, besides rotating aerators in the middle of the pool, add waterwheels to the poolside (about 3 meters offshore). The oxygen aerator makes the pool water form a micro-flowing water environment, which allows the shrimp to exercise more, speed up the metabolism, strengthen the constitution and increase the resistance to disease. It is necessary to diligently open the aerator so that the water in the pool can maintain high dissolved oxygen. This will not only promote the appetite and disease resistance of the shrimp, but also reduce the toxicity of ammonia, nitrite, hydrogen sulfide, and other toxic substances, so that the shrimp can maintain Strong vitality.
In addition, with the expansion of the aquaculture area and the increase in the number of seedlings, the original germplasm advantage of white shrimp is gradually weakening. At present, the white prawn virus disease (especially white spot syndrome) has become more common, and it is necessary to make the white prawn grow healthily. , but also regularly disinfect the body of water and internal medicine baits to prevent the occurrence of disease; regular testing of water quality indicators, to master the changes in water quality, prevent water quality deterioration. It is worth mentioning that there is information that the protein demand of white prawns on feed can be very low, and it turns out that this statement is not correct. If low-protein diet is fed, the white prawns will have very weak constitution and disease resistance. Poor, the breeding cycle is also longer, increasing the feed coefficient and production costs. Therefore, to ensure the healthy growth and stable yield of white shrimp, feed should be fed with more nutritious.
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