Gansu rainbow trout fish disease
Gansu is one of the earliest provinces in China to introduce rainbow trout trials (1977). Existing province rainbow trout fine seed farm, provincial cold water fish fine seed farm, Qilian snow cold water fish seed breeding center, Gannan Maqu rainbow trout farm, Bibo Hongyu fish farm, Yonglu county hydropower plant sturgeon fish farm, Yongchang County Beihaizi Hongyu fish farm Such large-scale farms and more than 240 households have workshop-style farms, with an aquaculture area of ​​270 mu and an annual output of 1,500 tons. Light Color Quarters Walnuts Kernels 1/4 Walnut Kernels , light color, broken while hand shelling .size is equal to or bigger than 1/4 walnut kernels, Light Color Quarters Walnuts Kernels,Light Color Walnuts Kernels,Hot Walnut Kernels Light,Walnut Kernels Light Quarters Weishan Yuanxing Walnuts Co.,Ltd. , https://www.walnutsxxy.com
Looking at the history of breeding in Gansu for 28 years, a lot of work has been done in the promotion and application of breeding techniques. At present, many farmers have accumulated a wealth of practical experience. At the same time, some scientific researchers and aquaculture technicians also made active and beneficial researches in the research on disease prevention and control of rainbow trout and achieved certain results, which in turn provide a strong force for the healthy development of the recuperation industry in Gansu. Technical support.
Now I have combined my own 20 years of scientific research on raising fish, to introduce the prevention and treatment of rainbow trout in Gansu province.
First, research status
Although the history of raising crickets in Gansu is relatively long, it is not long before the research on the prevention and control of rainbow trout disease has been conducted. There is still no professional institution or team for fish disease prevention research. Therefore, there is no way to discuss the special research funds for this purpose. From. In the relatively large number of eel raising groups, there are few people who specialize in research on disease prevention and control. In spite of this, some technical personnel who are interested in raising their apes have closely linked production practices and overcome various difficulties. They have conducted targeted research work and have achieved encouraging results. There are:
1. Rainbow Trout Infectious Pancreatic Necrosis (IPN) Together with specialists from Lanzhou Military Medical Research Institute, Lanzhou Veterinary Research Institute of Chinese Academy of Sciences, Shanghai Fisheries University and other research institutes, we have successfully tackled infectious diseases. Pancreatic necrosis virus, successfully isolated the pathogen (IPNV-sp strain), and made in-depth study of pathogenic characteristics, epidemiology, pathology and prevention methods. It was pointed out that the virus can penetrate fish eggs and cause vertical transmission through the eggs. Specific prevention and control measures are proposed: strict quarantine should be introduced when introducing ophthalmic eggs to prevent the introduction of viruses; fish farms with this disease should pay attention to purifying broodstock, and strengthen disinfection of water sources, polluted ponds and fishing gear, and cut off the transmission route. . That is, the incubator equipment and utensils are completely sterilized with bleaching powder before the start of hatching. Floating juveniles are fed to the pool and soaked in bleaching powder beforehand. When symptoms are found, they are immediately disinfected with 5 g/m3 bleach for 30 to 40 minutes. Relieve and then disinfect the body of water and fish body with bleaching bag hanging method; at the same time strengthen feeding and management, improve feed nutrition, increase vitamin B1, vitamin C content, can increase the survival rate of juvenile fish to 88%, the effect is very obvious.
2. The bacterial rickets of juvenile rainbow trout have made a careful observation on the pathogenic characteristics and pathogenesis. Havobacteri Um branchiophila is considered to be a hemolytic bacillus, which is widely found in fish ponds and natural water bodies. When rainbow trout fry is fed excessively for a long time, it often results in enteritis disease, and fish fry with enteritis disease rarely eats and even stops feeding. However, the fry stage is the fastest growing stage in rainbow trout and requires a sufficient and nutritious food supply. This creates a pair of irreconcilable contradictions, the result of which is that in a short period of time the fry's constitution is reduced, and the resistance to disease is reduced. Because of the affinity of F. falciparum to the tissues of rainbow trout, this type of bacteria in the water accumulates and erodes and destroys the locules, and then enters the blood from the wound, dissolves blood cells, reduces the number of red blood cells, and reduces the oxygen load. . Although there was no lack of dissolved oxygen in the water (>6 mg/l), the diseased fry still showed a rapid respiratory rate and a severe lack of oxygen. Therefore, it is a conditional pathogen, when the culture density is too high, the water environment is deteriorated (NH3, H2S, Zn content exceeds the standard, DO decreases, the water quality is turbid), and the disease is triggered when the immune function of the fish is reduced.
Since the tolerance of the bacteria to salt is 0 to 1%, juvenile fish bacterial rickets caused by the bacteria can be cured by simply bathing with 50 g/L salt water; however, in most cases, Bacterial disease in fish is often complicated by enteritis. For this reason, internal and external combined treatments are required to achieve the desired therapeutic effect.
3. Postpartum death of rainbow trout broodstock The high mortality rate of rainbow trout broodstock is a common problem encountered in rainbow trout breeding grounds in China. According to the survey, more than 10 rainbow trout species breeding grounds in the whole province, including the Yuzhong County Rainbow Trout Testing Ground, have a postmortem mortality of more than 10%. It has been pointed out that the mortality rate of broodstock after breeding is 15% to 20%, such as rainbow trout, golden trout, hard head louse, brown trout and red trout. The author developed a postpartum broodstock injection of penicillin, and then soaked with 10% saline for 15 to 20 seconds of comprehensive therapy, the mortality rate can be controlled within 1%. In addition, the wounded area healed quickly. Generally, after half a month to more than 20 days, the appetite can be completely restored. In the past 10 years, this efficacy has also been verified in some domestic rainbow trout species.
4. Rainbow trout liver injury is mainly due to intake of fat oxidized feed or nutrient incomplete feed, so that liver cells are damaged, liver dysfunction, metabolic imbalance occurs, causing a large number of fish death. The disease has occurred in various levels in all breeding farms and most of the country's breeding farms. Juvenile fish, adult fish, and broodstock feeding stages can occur. The loss is heavy. Using the theory of traditional Chinese medicine, the author boldly carried out research on prevention and treatment of Chinese herbal medicine. Through repeated trials, the authors screened the ideal treatment prescription “Yangchen Sanhuang Decoction†and successfully applied it to the rainbow trout, golden pheasant, silver bream and Atlantic salmon in our province and Heilongjiang province. The liver damage treatment of squid made a positive attempt for Chinese herbal medicine to prevent fish diseases.
5. The phenomenon of rainbow trout and different food is the abnormal feeding behavior of rainbow trout, such as sand, stone, wood fiber and silt. Due to the presence of large amounts of the above-mentioned foreign substances (0.45% to 7.85% of body weight) in the stomach, pylorus, and intestine of fish, the load on the fish is increased, and the fish's appetite is greatly reduced or disappeared due to strong stimulation and even damage to the digestive organs. Severely obstructed, thus reducing the economic benefits of raising apes. This phenomenon mainly occurs in the adult and broodstock rearing stages. The cause of the disease is the severe deficiency or lack of some nutrients in the feed. This has a certain relationship with the cultivation of heavy seedlings of breeders, the neglect of adult fish and the appropriate matching of feeds during the broodstock rearing period. The prevention and control method is to adjust the feed formula and feed it with high quality full-priced feed.
6. Nutritional liver disease and myopathy of rainbow trout Through a large number of anatomical and histological observations and trace element determination and analysis, the concept of nutritional liver disease and myopathy was first proposed. Preliminary findings suggest that the lack of vitamins and minerals (such as selenium) or excessive (such as copper) in feed may be the main cause of fish morbidity and mortality. The disease is not contagious. The incidence of fish from fry to commercial fish is as high as 60%, and the mortality rate is 40% to 80%. Severe cases cause devastating losses on farms (households).
We want to determine the main causes of nutritional liver disease and myopathy that afflict rainbow trout culture through etiological and pathological studies. Based on this, we will develop feed formulations and processing techniques to develop mineral and vitamin feed additives that are suitable for the nutritional needs of rainbow trout. Screening of drugs with small side effects, prevention and treatment of drugs with less residue in the body, and formulation of standardized technical standards for effective prevention and treatment of rainbow trout in the breeding process, and solving the main disease that restricts the development of rainbow trout in our province.
In addition to the above research work on rainbow trout nutritional hepatopathy and myopathy, other research results have been widely used in production and have achieved significant economic benefits.
In addition, the prevention of enteritis disease caused by the addition of fresh feed to the broodstock feed during the production process, the larval feeding time during hatching, the prevention of nutrient diseases of the fish fry, and the adaptation of catfish to temperature difference, The impact of fat and thin fish on the survival rate of transportation, purification treatment of hatchery water, prevention of premature male fish, and increased intermuscular stab of rainbow trout have also been studied, and first-hand data have been obtained to provide aquaculture production. Mature technical guidance and valuable experience.
It is not difficult to see from the above research situation that in rainbow trout farming in Gansu, most of the diseases are nutritional diseases, which is precisely the problem that farmers are most likely to overlook. At the same time, this also reflects that the production level of eel raising in Gansu is still relatively low, that is, most farmers still use traditional self-purchased raw materials, self-processed feed production, and workshop-style farming methods, which inevitably lead to nutrition. The occurrence of disease.
Second, prospects
High-density culture is the biggest advantage of rainbow trout, and the environmental deterioration caused by aquaculture water in this country is difficult to achieve scientific regulation due to low productivity levels in China. Coupled with the lagging of feed formulation and processing technology, rainbow trout's disease types will become more The more you lose, the more you lose. According to the National Aquatic Technology Extension Station, the incidence of rainbow trout in China was as high as 37.5% in 2003, ranking the first among aquaculture animals. Some of these diseases have caused devastating disasters on the farms and the losses are extremely heavy. Therefore, in a certain sense, whether scientific and effective prevention and control of diseases is a key factor that restricts the further development of raising aquaculture production.
Gansu is a relatively poor province in the western region. Over the years, the capital investment in breeding facilities has been very limited. Therefore, this kind of workshop-style backward production that currently dominates the production of rainbow trout in Gansu Province will not be possible in the next few years. The big change, that is, to realize the commercialization of raising feed, has a long way to go. Therefore, it can be foreseen that the disease and the degree of damage of the disease, especially the nutritional diseases, in Gansu Province will be even worse than in the whole country. The disease prevention and control situation faced by raising the eel will remain severe in the future.
Cold water resources in Gansu are relatively abundant, but as far as the province is concerned, cold springs currently use less than 20%. In addition, there are 270,000 mu of cold-water low-temperature reservoir suitable for trout farming. Therefore, in the future, the advantages and development priorities of Gansu fishery will still be cold-water fish farming such as earthworms. In view of this, it is particularly important to pay attention to and strengthen the research on carp disease prevention and control.
The author believes that in the future, the research on disease prevention and control should be included in the agenda, and as the emphasis on aquaculture production, the construction of corresponding institutions should be accelerated, necessary funds must be allocated, and prospective studies should be conducted on major diseases that endanger aquaculture production. At the same time, we must strengthen fish disease detection and quarantine work, and do a good job in quarantine from the source during production. We must ensure that fisheries, fingerlings, and broodstock that carry viral diseases are not used in fisheries production in our province; we must promote popularization and prevention of fish diseases. Provide scientific guidance and assistance for the healthy breeding of carp, so that the eel farmers are protected from unnecessary economic losses. Only in this way can the rapid and healthy development of the breeding industry in Gansu.