JPH0542901B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a feed for cultured fish containing egg antibodies that specifically bind to pathogens of fish infectious diseases and have the effect of reducing or eliminating the infectivity of the pathogens. [Prior Art] In recent years, fishing catches have been decreasing due to the 200 nautical mile problem and a shortage of fish resources due to overfishing. Furthermore, with advances in aquaculture technology, Japan's fishing industry is rapidly changing from catching fish to growing fish. As fish consumption increases in response to the health-oriented diet of the nation, fisheries are responding to market demand through large-scale aquaculture. Under these circumstances, the damage caused by infectious diseases to farmed fish has increased and has become a major problem. Infectious diseases in farmed fish are often caused by bacteria and viruses. Specifically, Vibrio disease, nodular disease,
Streptococcus disease, red fin disease, paracolon disease, red spot disease, furrow disease, aeromonas infection, columnarisis,
Intestinal clouding, lymphocystosis, etc. may occur. These infections vary depending on the species of fish, but these infections affect yellowtail, sea bream, flounder, eel, shrimp, sweetfish, salmon, and other fish.
It occurs frequently during the juvenile or adult stages of trout, carp, etc. These fish are cultivated on a large scale, and once an infectious disease occurs, the damage caused is enormous. Therefore, it is of great significance to develop ways to prevent it. Conventionally, these fish infectious diseases have been prevented using antibiotics such as oxolinic acid and oxytetracycline. [Problems to be solved by the invention] There are many problems in preventing fish infections using antibiotics. First, antibiotics cannot be expected to be effective against viruses. Furthermore, with respect to bacteria, there is a problem of the emergence of resistant bacteria. Bacteria resistant to antibiotics currently approved for use in farmed fish are being discovered every year. Next, there is the issue of antibiotic residue in farmed fish. Although their usage and dosage are strictly regulated by law, consumers in recent years have become particularly sensitive to the problem of antibiotic residue, and view the use of antibiotics in farmed fish as problematic. Furthermore, after using antibiotics, farmed fish cannot be shipped to the market for about six months to one month. Currently, there is no preventive method for infectious diseases that occur during this period. Under these circumstances, there is a desire to develop new preventive methods to replace the use of antibiotics for fish infections. The use of specific antibodies is being investigated as a new preventive method for fish infections as an alternative to the use of antibiotics. Antibodies specific to pathogens of fish infectious diseases are thought to reduce or eliminate infectivity by binding to the corresponding pathogens. Generally, specific antibodies are obtained from the blood of animals such as rabbits and goats that are immunized with bacteria or viruses that serve as antigens. However, this method is difficult to mass produce and is expensive, so its industrial use is not realistic. Therefore, there are many problems in using specific antibodies obtained from blood as feed for cultured fish. Therefore, prevention of fish infectious diseases using specific antibodies has not been put into practical use at present, and no practical method for preventing fish infectious diseases that can replace the use of antibiotics has yet been developed. [Means for solving the problem] It is known that avian antibodies migrate into egg yolk. Therefore, by immunizing chickens with a certain antigen, antibodies specific to that antigen can be obtained from the egg yolk. This fact has been published in literature for a long time and is well known [Patterson, R. et al.
J.Immunol.
Volume 89, page 272 (1962): Orlans,
E.) Immunology, Vol. 12, p. 27 (1967): Polson, A., et al., Immunol.
Commun.) Vol. 9, p. 475 (1980); Polson, A. et al., Immunol. Commun., Vol. 9, p. 495 (1985)]. Chicken eggs have many advantages when considered as a raw material for specific antibodies. First, it eliminates the need for whole blood collection from animals, which requires advanced techniques. Specific antibodies can be collected simply by collecting eggs without having to kill animals. Furthermore, chickens can be raised in large numbers in a small space. One chicken lays 250-300 eggs per year.
The specific antibody content in the egg yolk is comparable to that in blood. Also, chicken eggs are cheap. Therefore, using chicken eggs is very practical in terms of mass production and effective use of specific antibodies. However, feed for cultured fish using specific antibodies in chicken eggs has not yet been developed. The present inventors thought that by using chicken egg antibodies specific to the pathogens of fish infectious diseases, it might be possible to prepare feed for farmed fish that has a preventive effect against the corresponding fish infectious diseases, and worked diligently to Researched. That is, chickens were hyperimmunized with a fish infectious disease pathogen, and eggs produced by the chicken were made to produce egg antibodies specific to the pathogen. Next, when they prepared and tested feed for cultured fish containing chicken eggs containing the specific chicken egg antibody, they found that it had a remarkable preventive effect against the corresponding infectious diseases, and thus completed the present invention. . [Effect] Egg antibodies specific to the pathogen of fish infectious diseases used in the present invention are obtained in the egg yolk of chicken eggs produced by chickens hyperimmunized with the pathogen as an antigen. It may be in any form such as a liquid or dried whole egg powder or egg yolk powder by a commonly used method. Specifically, the pathogens of fish infections that serve as antigens include Aeromonas bacteria that cause Aeromonas infections, Vibrio bacteria that cause Vibrio disease and intestinal clouding, Pasteurella bacteria that cause nodular disease, and Edwards bacteria that cause Paracoloosis. These include bacteria of the genus Ziella, Streptococcus that causes streptococcus disease, and Lymphocystis virus that causes Reliphocystis disease. When pathogens of fish infectious diseases have been isolated in this way, a suspension of one or more types of pathogens obtained by culturing them in an appropriate medium may be used as an antigen. Alternatively, antigenic determinants on the surface of these bacteria or viruses may be purified and used as antigens.
For those for which the pathogen has not been determined, a homogenate of the affected part of a fish infection can be used as an antigen. Bacteria and viruses isolated therefrom also serve as antigens. To immunize chickens, the general methods are to spray the antigen and sensitize it through the eyes and nostrils, to sensitize it by giving water or feed containing the antigen orally, and to immunize the antigen by administering it intramuscularly, subcutaneously, intradermally, or intravenously. The method of sensitization by injection is being used. When using a fish infectious disease pathogen as an antigen, chickens may be made hyperimmune using any of these methods. To make chickens hyperimmune, booster immunizations may be given two or three times at intervals of one or two weeks after the initial immunization. Due to this hyperimmunity, the specific antibody titer in chicken eggs reaches its highest value. This maximum value is usually maintained for 2 to 4 months. If a decrease in antibody titer is observed, a booster immunization will be given once, which will last another 2 months or more.
The highest antibody titer is maintained for 4 months. Therefore, by hyperimmunizing chickens using pathogens of fish infectious diseases as antigens and repeating booster immunizations at appropriate intervals, it is possible to obtain antibodies specific to the pathogen that always show the highest specific antibody titers during the chicken's egg-laying period. Eggs containing chicken egg antibodies can be obtained. Whole egg liquid or egg yolk liquid or whole egg powder or egg yolk powder of chicken eggs obtained as above,
The specific chicken egg antibody of the present invention can be blended with raw materials commonly used in feed for farmed fish, such as vitamins and minerals, carbohydrates, lipids, proteins, and attractants for farmed fish necessary for the growth of farmed fish. Feed for farmed fish can be obtained. The amount of the specific chicken egg antibody to be mixed is appropriately determined depending on the specificity for the pathogen of the fish infection, the antibody titer, etc. Next, the present invention will be further explained in detail with reference to Test Examples and Examples. Test Example 1 Immunization of chickens using pathogens of fish infections. Pasteurella piscicida, a pathogenic bacterium that causes nodularity, was cultured at 25°C for 48 hours in brain heart infusion medium containing 2% salt, then inactivated with 0.5% formalin, and the killed bacterial suspension was used as an antigen. . For immunization, 50 chickens aged 130 days were used, and approximately 10 ⁸ killed Pasteurella piscicida bacteria were inoculated into the leg muscles of each chicken. After the initial immunization, booster immunizations were repeated three times once a week. Subsequent booster immunizations were given once every two months. 10 eggs from immunized chickens every 2 weeks
The egg yolk was selected for its agglutinating antibody titer against Pasteurella piscicida. Figure 1 shows the changes in the agglutinated antibody titer due to immunization. In the present invention, the agglutinated antibody titer was measured by first diluting the egg yolk solution 8 times with a carrageenan solution (1 mg/ml), selectively precipitating egg yolk lipoproteins, and separating the supernatant containing egg antibodies by centrifugation. . The agglutinated antibody titer was measured using the macrotiter method using this supernatant as an 8-fold diluted egg yolk solution. Test Example 2 Examination of heat sterilization and spray drying conditions for egg yolk liquid containing specific chicken egg antibodies. Egg yolks were collected from the chicken eggs of Test Example 1 and diluted 1.5 times with water to reduce viscosity. Using this 1.5-fold diluted egg yolk solution, pasteurella and
Changes in the agglutinating antibody titer specific to killed P. piscicida were investigated. The results are shown in Table 1.

[Table] From the above results, the general sterilization conditions for egg yolk liquid,
It was shown that 63°C for 3.5 minutes did not affect the specific antibody titer in egg yolk. Next, using the above 1.5-fold diluted egg yolk that had been heat sterilized at 63°C for 3.5 minutes, changes in the agglutination antibody titer specific to killed Pasteurella piscicida were investigated under various spray drying conditions. Table 2 shows the results.
Shown below.

〔Effect of the invention〕

The feed for farmed fish of the present invention contains chicken egg antibodies specific to pathogens of fish infectious diseases, and has a preventive effect against the corresponding fish infectious diseases. The conventional prevention of fish infectious diseases through the use of antibiotics can be partially or completely replaced by using the feed for cultured fish of the present invention. Moreover, since the feed for cultured fish of the present invention contains egg components, it also has the advantage of being high in nutritional value. Generally, farmed fish are susceptible to infectious diseases when they are young. When the cultured fish feed of the present invention is used during the fry stage, it can be expected to not only prevent the corresponding infectious diseases but also promote the growth of the fry due to the high nutritional value of chicken eggs. The feed for farmed fish of the present invention contains chicken egg antibodies specific for the pathogen of a fish infectious disease, which are obtained from eggs produced by chickens hyperimmunized with the pathogen. The present inventors were the first to apply such a specific chicken egg antibody to feed for cultured fish. Blood antibodies obtained from the blood of hyperimmune animals are usually considered as antibodies specific to pathogens of fish infections. This is difficult to mass produce and is also cheap, making feed for aquaculture fish using it impractical in terms of price. In the present invention, whole egg fluid, egg yolk fluid, or their dry powders containing chicken egg antibodies are used as antibodies specific to pathogens of fish infectious diseases. Therefore, the feed for cultured fish of the present invention can be prepared in large quantities, is inexpensive, and is very practical.

[Brief explanation of the drawing]

Figure 1 shows changes in the specific antibody titer contained in the yolks of eggs produced by chickens immunized with Pasteurella piscicida.

Claims (1)

[Scope of Claims] 1. Feed for cultured fish containing chicken egg antibodies specific to pathogens of fish infectious diseases. 2. The feed for farmed fish according to claim 1, wherein the egg antibody is whole egg fluid or egg yolk fluid of chicken eggs produced by chickens hyperimmunized with a pathogen of a fish infectious disease. 3. The feed for cultured fish according to claim 1, wherein the egg antibody is whole egg powder or egg yolk powder of chicken eggs produced by chickens hyperimmunized with a pathogen of a fish infectious disease.