Pond ecological management and its nutrient supply Macrobrachium rosenbergii is an excellent freshwater aquaculture species. Since the introduction of China in the late 1970s, its production and cultivation have been rapidly developed, and now it has been radiated to Guangdong, Guangxi, Hubei, Jiangsu, Zhejiang and Anhui. Heyu and Other more than 10 provinces, municipalities and autonomous regions, its farming model is increasingly large-scale and industrialization. However, the frequent occurrence and prevalence of shrimp disease has plagued the development of shrimp farming. With the development of Intensive Macrobrachium rosenbergii, many experts and scholars at home and abroad have done a lot of detailed research on the causes of shrimp disease, the preventive measures of epidemic characteristics, and the nutritional needs of Macrobrachium rosenbergii. By improving its nutrient supply for diets and optimizing the ecological environment of shrimp ponds, preventing diseases and reducing the risk of breeding, improving economic efficiency has become an important part of the intensive aquaculture industry. The exploration of the ecological environment management and nutrient requirements of Macrobrachium rosenbergii will help guide the aquaculture production.
Nutritional needs for diets The growth of shrimp depends not only on the environment in which it grows, but also on the quality of its diet. High-quality diets can meet the growth needs of shrimp and improve its immunity.
First, protein and amino acid needs
1. Protein needs protein as a carrier of life, which occupies an irreplaceable role in the nutritional needs of Roche shrimp, and the protein content of the bait directly affects its growth and development. In the absence of protein, its growth and development are hindered, the body's resistance is reduced, and even death; protein levels are too high, protein resources are wasted, and the nitrogen source emitted pollutes the culture environment because the body cannot convert excess protein into its own protein. Millikin et al. (1980) reared lobster juvenile shrimps with round belly pupa and soybean protein as the protein source and round belly oyster oil/corn oil (2:1) as the fat source compound feed. The results showed that the test group with a crude protein level of 40.2% had significant weight gain. Cao Zhilan (1989) showed that the technical and economic indicators of 35.6% protein content in Roche shrimp were superior to those in the two groups with protein levels of 32.19% and 27.44%, respectively. Zhu Yazhu et al. (1995) used juvenile shrimp as a gradient test. The results showed that the test group with a protein level of 50% in feed has the best growth effect (casein and fish meal are protein sources).
The Roche shrimp's need for dietary proteins is influenced by factors such as its growth stage, environmental conditions and feeding methods. Different experimental conditions and influencing factors have different requirements for proteins. When the natural bait is rich, the bait protein can be appropriately reduced, the protein level can be about 26%-28%; in the case of natural bait shortage or feeding period can not fertilize, the bait protein level should be increased by 5-10% should. The protein content of Roche shrimp in the Yangtze River Delta is about 30%-35%, and that in the Pearl River Delta is about 36%-38%, and the ratio of animal to vegetable protein is 1:4.
2. Amino acids require the nutritional needs of Roche shrimp for essential amino acids. At present, research data at home and abroad are rare. Some scholars have made experiments on missing or adding lysine and methionine, but the results are not the same.
Second, lipids need lipids as an important component of animal nutrition, especially for aquaculture, which not only provides the energy needed for growth and life-sustaining activities, but also saves dietary protein, and the essential fatty acids contained therein are necessary for shrimp growth. of. Domestic and foreign research data show that the amount of lipids in Roche shrimp bait is related to the quality of feed protein and the balance of feed energy and essential amino acids. The variation is generally between 2% and 10%, and the suitable content is between 6% and 8%. Linoleic acid and linolenic acid are essential fatty acids in Roche shrimp, which may differ from seawater. The essential fatty acids of Roche shrimp are closer to those of tropical fish such as African squid, and nutrients need more n-6 series of high melting point unsaturated fatty acids.
Joseph et al. (1976) fed the young shrimp with 3% linolenic acid-rich shrimp head oil, which grew best. Millikin et al. (1980) used squid oil and corn oil as a fat source to mix fish meal and soybean meal to feed Roche shrimp. It was found that a feed group containing 10.5% lipids and a sugar to fat ratio of 3.5 had a good effect on shrimp growth. . Sheen and Abramo (1991) found that when a mixture of waxy liver oil and corn oil (2:1) was added as a lipid, the 6% lipid diet of Roche shrimp grew fastest, above or below 6%, and Roche shrimp grew slowly. Even suppressed. In order to further study the nutritional needs of shrimps with unsaturated fatty acids, Abramo and Sheen (1993) fed PUFA with Roche shrimp and found that it can promote the growth of shrimp. PUFA with a carbon content of more than 20 is more effective in promoting the growth of shrimp, and in shrimp body tissues. The content of saturated fatty acids and monounsaturated fatty acids is related to the amount of PUFA added. Wu Ruiquan et al. (2000) fed Roche shrimp with diets mainly composed of casein and fishmeal, and found that 5% lipids were more suitable, which is similar to the conclusion drawn by Zheng Shuhe et al. (1995).
Hilton et al. (1984) added 0%-10% lecithin to the diet of larvae containing 1% cholesterol and found that the addition of lecithin had no significant effect on the growth and survival rate of shrimp. It shows that Roche's demand for cholesterol and lecithin is different from that of marine crustaceans. Roche shrimp do not need to add cholesterol and lecithin.
Third, the needs of carbohydrates Roche shrimp at different stages of development of carbohydrate dietary changes in demand, the suitable range of 22% -30%. Compared with monosaccharides, Roche shrimp can use complex carbohydrates more effectively. Baslaz et al. (1976) used high amylose starch as a binder for juvenile shrimp bait tests, with better survival and feed efficiency. Dlaz et al. (1990) fed potato flour, soluble starch, dextrin, sucrose, and glucose, respectively, as carbohydrates to about 2.0 grams of juvenile shrimp. The results showed that the growth of starch was the best, and the feed conversion rate and protein efficiency were both high. The highest, followed by dextrin, sucrose, and glucose were the worst. The carbohydrate content and source in the diet also affect the composition of the shrimp body tissue composition and its absorption and utilization of other components. When the lipid to carbohydrate ratio is 1:3-1:4, the shrimp can effectively use the dietary protein Clifferd, etc. 1979).
Roche shrimp can secrete cellulase in the intestine, and it is better to use dietary cellulose, so cellulose can be added as food fiber to crustacean diet. The diet containing 20% ​​cellulose had a stimulatory effect on sexually mature shrimp. In the feed, cellulose was used instead of part of the starch to feed Roche shrimp, and no adverse growth effects were observed (Fair et al., 1980). It can be seen that a certain amount of cellulose (6% to 24%) is contained in the shrimp feed, which is beneficial to the growth of the shrimp and also helps to reduce the cost of cultivation.
Fourth, the needs of inorganic salts and vitamins Roche shrimp nutritional requirements of inorganic salts and vitamins research at home and abroad reported less, usually in the feed to add their own preparation of inorganic salts and vitamin feed additives, the difference is greater. Studies have found that the suitable amount of inorganic salt in Roche shrimp diet is as high as 10%-13%. Rath and Dube (1994) studied that the optimum addition amount of Roche shrimp is 9%.
D, abramo et al. (1994) designed different gradients to study the nutritional requirements of vitamin C in Roche shrimp. The results showed that the vitamin C content increased from 0 to 10010-6 and the survival rate of Roche shrimp increased gradually. The appropriate requirement for vitamin C is 104 mg/kg feed. Japan, Europe, and the United States have different levels of inorganic salt minerals and multivitamins added to Roche shrimp. They are used for reference only. Management and optimization of the pond's ecological environment The pond is the environment on which shrimp lives, and its ecology is The growth, survival and disease resistance of good shrimp have a significant impact. In view of the physiological and ecological characteristics of shrimp, the prevention of shrimp diseases should start from the cut off of transmission methods and reduce self-pollution, and do a good job in the management and optimization of the shrimp pond ecological environment, to maintain a good ecology of the shrimp pond.
First, cut off the route of transmission of pathogens
1. Sludge in ponds and shrimp ponds that have been sterilized and bred for a long time. After the harvest, the ponds are drained and the organic silt and contaminants are removed. After the sun is exposed, lime ploughs the bottom of the plough. Fresh pond sprinkle lime. The influent water was carried out about 15 days before planting. Water intake should be based on local water sources, select the appropriate drugs to disinfect the pool sugar and pool water. The method of disinfection is generally 25-30 cm in the shrimp pond water, choose sunny morning or noon with chlorine dioxide 0.8-0.9 mg / l disinfection. After sterilizing, the water was rinsed twice the next day. The water intake was about 40 cm, and it was disinfected with rapeseed cake (20-25 ppm). Finally in the water 0.9-1.0 meters, and then disinfected with chlorine dioxide disinfectant (0.2-0.3ppm), and keep the water level unchanged, 3-4 days after the creation of water.
2. After proper water control methods are adopted to stock healthy shrimp, proper water control is very important. With the intensification of self-pollution, the traditional large-scale water-changing aquaculture has shown its limitations due to the decline of surrounding exogenous water quality, large amount of bacteria, and poor physical and chemical indicators. Closed or semi-closed methods are gradually accepted and adopted by farmers, that is, little or no water change is required in the breeding process. However, due to evaporation or leakage of water, the water level drops, and fresh water can be introduced into the pool. However, shrimp ponds that need to be diverted need to disinfect pool water with disinfectants with small toxic and side effects, and three days later, beneficial microbiological agents such as probiotics should be applied.
Second, reduce self-pollution
1. The density of the cultivation is suitable. Any one of the ecosystems has its own specific optimal environmental capacity. In a shrimp pond, the holding capacity of the shrimp pond is limited by pond conditions such as depth, oxygen content, and water quality. To increase production, a reasonable culture density and the survival rate of shrimp are crucial. The suitable breeding density can reduce the accumulation of shrimp excrement and residual bait in the pond, which is conducive to maintaining a good pond ecological environment. Under normal circumstances, 1.5 meters water level, stocking about 20,000 per acre, intensive breeding ponds 3.5-4.5 million tail stocking per acre is appropriate.
2. Cultivate algae and keep the water suitable for transparency. Develop excellent algae such as planktonic diatoms and green algae, create a good water color, provide palatability and natural food for shrimp, and promote the growth and survival of shrimp is an important part of healthy breeding. After disinfecting the ponds and bodies of water, fertilizers and Bacillus complex preparations that are not adsorbed by the sediments and have a reasonable ratio are used. After 5-7 days, a good water color can be created before the plants are released.
3, high-quality food, feeding methods Science and high-quality food not only rich in protein, amino acid balance, but also rich in vitamins, highly unsaturated fatty acids, cholesterol, trace elements, etc., its comprehensive nutrition, uniform particles, water softening speed, good stability, It helps to increase the food intake of shrimp, promote the growth of shrimp and normal shelling. When feeding the feed, the whole pool should be evenly distributed and less meals should be fed. It is advisable that the shrimp can eat enough within one hour.
4. Use of beneficial microbial preparations to regulate the ecology of the pond During the culture process, only 30% to 40% of the feed fed is converted into body protein, and the rest is converted into organic or inorganic substances into the shrimp pond. Due to the fact that shrimp production basically adopts a closed or semi-closed mode, the pond's own microflora alone cannot timely degrade the pond's dirt. Therefore, a large amount of body excrement, residual bait, and plankton remnants are accumulated in ponds after 3 months, resulting in anaerobic and anaerobic ponds, facultative anaerobic microbes, and deterioration of the ecological environment. The use of beneficial microorganism preparations can effectively solve the above-mentioned problems and improve the ecological environment. Beneficial microorganisms include PSB, nitrifying bacteria, Bacillus, etc. Especially, Bacillus can secrete digestive enzymes, degrade organic contaminants, balance algal phases, increase dissolved oxygen, reduce ammonia and other toxic factors, and inhibit the growth of bacteria and harmful bacteria.
Nutritional needs for diets The growth of shrimp depends not only on the environment in which it grows, but also on the quality of its diet. High-quality diets can meet the growth needs of shrimp and improve its immunity.
First, protein and amino acid needs
1. Protein needs protein as a carrier of life, which occupies an irreplaceable role in the nutritional needs of Roche shrimp, and the protein content of the bait directly affects its growth and development. In the absence of protein, its growth and development are hindered, the body's resistance is reduced, and even death; protein levels are too high, protein resources are wasted, and the nitrogen source emitted pollutes the culture environment because the body cannot convert excess protein into its own protein. Millikin et al. (1980) reared lobster juvenile shrimps with round belly pupa and soybean protein as the protein source and round belly oyster oil/corn oil (2:1) as the fat source compound feed. The results showed that the test group with a crude protein level of 40.2% had significant weight gain. Cao Zhilan (1989) showed that the technical and economic indicators of 35.6% protein content in Roche shrimp were superior to those in the two groups with protein levels of 32.19% and 27.44%, respectively. Zhu Yazhu et al. (1995) used juvenile shrimp as a gradient test. The results showed that the test group with a protein level of 50% in feed has the best growth effect (casein and fish meal are protein sources).
The Roche shrimp's need for dietary proteins is influenced by factors such as its growth stage, environmental conditions and feeding methods. Different experimental conditions and influencing factors have different requirements for proteins. When the natural bait is rich, the bait protein can be appropriately reduced, the protein level can be about 26%-28%; in the case of natural bait shortage or feeding period can not fertilize, the bait protein level should be increased by 5-10% should. The protein content of Roche shrimp in the Yangtze River Delta is about 30%-35%, and that in the Pearl River Delta is about 36%-38%, and the ratio of animal to vegetable protein is 1:4.
2. Amino acids require the nutritional needs of Roche shrimp for essential amino acids. At present, research data at home and abroad are rare. Some scholars have made experiments on missing or adding lysine and methionine, but the results are not the same.
Second, lipids need lipids as an important component of animal nutrition, especially for aquaculture, which not only provides the energy needed for growth and life-sustaining activities, but also saves dietary protein, and the essential fatty acids contained therein are necessary for shrimp growth. of. Domestic and foreign research data show that the amount of lipids in Roche shrimp bait is related to the quality of feed protein and the balance of feed energy and essential amino acids. The variation is generally between 2% and 10%, and the suitable content is between 6% and 8%. Linoleic acid and linolenic acid are essential fatty acids in Roche shrimp, which may differ from seawater. The essential fatty acids of Roche shrimp are closer to those of tropical fish such as African squid, and nutrients need more n-6 series of high melting point unsaturated fatty acids.
Joseph et al. (1976) fed the young shrimp with 3% linolenic acid-rich shrimp head oil, which grew best. Millikin et al. (1980) used squid oil and corn oil as a fat source to mix fish meal and soybean meal to feed Roche shrimp. It was found that a feed group containing 10.5% lipids and a sugar to fat ratio of 3.5 had a good effect on shrimp growth. . Sheen and Abramo (1991) found that when a mixture of waxy liver oil and corn oil (2:1) was added as a lipid, the 6% lipid diet of Roche shrimp grew fastest, above or below 6%, and Roche shrimp grew slowly. Even suppressed. In order to further study the nutritional needs of shrimps with unsaturated fatty acids, Abramo and Sheen (1993) fed PUFA with Roche shrimp and found that it can promote the growth of shrimp. PUFA with a carbon content of more than 20 is more effective in promoting the growth of shrimp, and in shrimp body tissues. The content of saturated fatty acids and monounsaturated fatty acids is related to the amount of PUFA added. Wu Ruiquan et al. (2000) fed Roche shrimp with diets mainly composed of casein and fishmeal, and found that 5% lipids were more suitable, which is similar to the conclusion drawn by Zheng Shuhe et al. (1995).
Hilton et al. (1984) added 0%-10% lecithin to the diet of larvae containing 1% cholesterol and found that the addition of lecithin had no significant effect on the growth and survival rate of shrimp. It shows that Roche's demand for cholesterol and lecithin is different from that of marine crustaceans. Roche shrimp do not need to add cholesterol and lecithin.
Third, the needs of carbohydrates Roche shrimp at different stages of development of carbohydrate dietary changes in demand, the suitable range of 22% -30%. Compared with monosaccharides, Roche shrimp can use complex carbohydrates more effectively. Baslaz et al. (1976) used high amylose starch as a binder for juvenile shrimp bait tests, with better survival and feed efficiency. Dlaz et al. (1990) fed potato flour, soluble starch, dextrin, sucrose, and glucose, respectively, as carbohydrates to about 2.0 grams of juvenile shrimp. The results showed that the growth of starch was the best, and the feed conversion rate and protein efficiency were both high. The highest, followed by dextrin, sucrose, and glucose were the worst. The carbohydrate content and source in the diet also affect the composition of the shrimp body tissue composition and its absorption and utilization of other components. When the lipid to carbohydrate ratio is 1:3-1:4, the shrimp can effectively use the dietary protein Clifferd, etc. 1979).
Roche shrimp can secrete cellulase in the intestine, and it is better to use dietary cellulose, so cellulose can be added as food fiber to crustacean diet. The diet containing 20% ​​cellulose had a stimulatory effect on sexually mature shrimp. In the feed, cellulose was used instead of part of the starch to feed Roche shrimp, and no adverse growth effects were observed (Fair et al., 1980). It can be seen that a certain amount of cellulose (6% to 24%) is contained in the shrimp feed, which is beneficial to the growth of the shrimp and also helps to reduce the cost of cultivation.
Fourth, the needs of inorganic salts and vitamins Roche shrimp nutritional requirements of inorganic salts and vitamins research at home and abroad reported less, usually in the feed to add their own preparation of inorganic salts and vitamin feed additives, the difference is greater. Studies have found that the suitable amount of inorganic salt in Roche shrimp diet is as high as 10%-13%. Rath and Dube (1994) studied that the optimum addition amount of Roche shrimp is 9%.
D, abramo et al. (1994) designed different gradients to study the nutritional requirements of vitamin C in Roche shrimp. The results showed that the vitamin C content increased from 0 to 10010-6 and the survival rate of Roche shrimp increased gradually. The appropriate requirement for vitamin C is 104 mg/kg feed. Japan, Europe, and the United States have different levels of inorganic salt minerals and multivitamins added to Roche shrimp. They are used for reference only. Management and optimization of the pond's ecological environment The pond is the environment on which shrimp lives, and its ecology is The growth, survival and disease resistance of good shrimp have a significant impact. In view of the physiological and ecological characteristics of shrimp, the prevention of shrimp diseases should start from the cut off of transmission methods and reduce self-pollution, and do a good job in the management and optimization of the shrimp pond ecological environment, to maintain a good ecology of the shrimp pond.
First, cut off the route of transmission of pathogens
1. Sludge in ponds and shrimp ponds that have been sterilized and bred for a long time. After the harvest, the ponds are drained and the organic silt and contaminants are removed. After the sun is exposed, lime ploughs the bottom of the plough. Fresh pond sprinkle lime. The influent water was carried out about 15 days before planting. Water intake should be based on local water sources, select the appropriate drugs to disinfect the pool sugar and pool water. The method of disinfection is generally 25-30 cm in the shrimp pond water, choose sunny morning or noon with chlorine dioxide 0.8-0.9 mg / l disinfection. After sterilizing, the water was rinsed twice the next day. The water intake was about 40 cm, and it was disinfected with rapeseed cake (20-25 ppm). Finally in the water 0.9-1.0 meters, and then disinfected with chlorine dioxide disinfectant (0.2-0.3ppm), and keep the water level unchanged, 3-4 days after the creation of water.
2. After proper water control methods are adopted to stock healthy shrimp, proper water control is very important. With the intensification of self-pollution, the traditional large-scale water-changing aquaculture has shown its limitations due to the decline of surrounding exogenous water quality, large amount of bacteria, and poor physical and chemical indicators. Closed or semi-closed methods are gradually accepted and adopted by farmers, that is, little or no water change is required in the breeding process. However, due to evaporation or leakage of water, the water level drops, and fresh water can be introduced into the pool. However, shrimp ponds that need to be diverted need to disinfect pool water with disinfectants with small toxic and side effects, and three days later, beneficial microbiological agents such as probiotics should be applied.
Second, reduce self-pollution
1. The density of the cultivation is suitable. Any one of the ecosystems has its own specific optimal environmental capacity. In a shrimp pond, the holding capacity of the shrimp pond is limited by pond conditions such as depth, oxygen content, and water quality. To increase production, a reasonable culture density and the survival rate of shrimp are crucial. The suitable breeding density can reduce the accumulation of shrimp excrement and residual bait in the pond, which is conducive to maintaining a good pond ecological environment. Under normal circumstances, 1.5 meters water level, stocking about 20,000 per acre, intensive breeding ponds 3.5-4.5 million tail stocking per acre is appropriate.
2. Cultivate algae and keep the water suitable for transparency. Develop excellent algae such as planktonic diatoms and green algae, create a good water color, provide palatability and natural food for shrimp, and promote the growth and survival of shrimp is an important part of healthy breeding. After disinfecting the ponds and bodies of water, fertilizers and Bacillus complex preparations that are not adsorbed by the sediments and have a reasonable ratio are used. After 5-7 days, a good water color can be created before the plants are released.
3, high-quality food, feeding methods Science and high-quality food not only rich in protein, amino acid balance, but also rich in vitamins, highly unsaturated fatty acids, cholesterol, trace elements, etc., its comprehensive nutrition, uniform particles, water softening speed, good stability, It helps to increase the food intake of shrimp, promote the growth of shrimp and normal shelling. When feeding the feed, the whole pool should be evenly distributed and less meals should be fed. It is advisable that the shrimp can eat enough within one hour.
4. Use of beneficial microbial preparations to regulate the ecology of the pond During the culture process, only 30% to 40% of the feed fed is converted into body protein, and the rest is converted into organic or inorganic substances into the shrimp pond. Due to the fact that shrimp production basically adopts a closed or semi-closed mode, the pond's own microflora alone cannot timely degrade the pond's dirt. Therefore, a large amount of body excrement, residual bait, and plankton remnants are accumulated in ponds after 3 months, resulting in anaerobic and anaerobic ponds, facultative anaerobic microbes, and deterioration of the ecological environment. The use of beneficial microorganism preparations can effectively solve the above-mentioned problems and improve the ecological environment. Beneficial microorganisms include PSB, nitrifying bacteria, Bacillus, etc. Especially, Bacillus can secrete digestive enzymes, degrade organic contaminants, balance algal phases, increase dissolved oxygen, reduce ammonia and other toxic factors, and inhibit the growth of bacteria and harmful bacteria.
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