Causes of poor immune effect of chickens and its countermeasures

At present, the majority of households generally respond to the following problems: it is OK for ① not to be vaccinated, and chickens will get sick as soon as they are vaccinated. ② sometimes occurs in chicken flocks before they are vaccinated. No matter what kind of measures ③ takes, the immune effect of the vaccine is always poor.

Why do these problems arise? The reason is that the immune organs of chickens are damaged. After the damage to the immune organs of chickens, the resistance of the body to bacterial and viral infections decreases, and the flocks of chickens can easily cause a variety of epidemics and bring huge economic losses to the chicken industry. So what are the causes of immune injury? What are the countermeasures?

The main results are as follows: (1) the effect of immunosuppressive disease. Immunosuppressive disease affects the development of immune organs, inhibits the cloning and replication of vaccine in vivo, and interferes with the production of antibodies. Bursal disease is a common immunosuppressive disease. If the chicken gets bursal disease, it will interfere with the antibody of Newcastle disease, so it is very easy to be infected with Newcastle disease, so it should be replanted with Newcastle disease vaccine in time after the cure of bursal disease. Infectious gonadal gastritis, also known as reticuloendotheliosis, is also an immunosuppressive disease. The pathogen of the disease often pollutes the live vaccine, and is infected with the disease at the same time after vaccination, because the symptoms of the disease are atypical, and it is easy to lead to the decline of immunity, while other secondary diseases (such as colibacillosis, mycoplasma disease and Newcastle disease, etc.) often fail to cure due to missed diagnosis of the disease. Therefore, chicken farmers in vaccination (live vaccine) in addition to the use of anti-vaccine stress drugs (such as Luohong, Tyler, oxyfluoride), but also should not affect the potency of the vaccine, but also antiviral immune enhancers (such as astragalus polysaccharides, etc.) to prevent the occurrence of reticuloendotheliosis.

(2) the design of immunization program is unreasonable. Chicken farmers always want to have a foolproof immunization procedure, and a considerable number of chicken farmers attach great importance to learning new technology. when they see a new immunization program from the data, they will be immunized according to it. Some chicken farmers try their best to get other people's immunization procedures from large-scale chicken farms in other provinces and cities, thinking that their immunization procedures are perfect, so they should be immunized according to their own procedures. The immunization program must be designed according to the characteristics of the disease in this area and the epidemic disease at that time, which is the most reasonable.

(3) improper vaccine quality and vaccine selection. Poor or unstable quality of vaccine is the direct cause of immune injury. The vaccine was transported and preserved improperly, the vaccine was exposed to the scorching sun before immunization, exceeded the use time, took out too long, and the attenuated vaccine was not selected during the first immunization. however, the selection of moderately high virulence vaccine or the wrong vaccine during immunization will cause the immune operation and failure of different procedures and lead to the incidence of disease or the decrease of resistance to infection of other diseases. Therefore, the vaccine must choose the efficient vaccine produced by regular manufacturers (such as poultry vaccine must be produced by national designated manufacturers). At the same time, the transportation, preservation, selection and use of vaccine must be in strict accordance with the operating rules.

(4) the method of immunization and the dosage of vaccine are appropriate. The effect of different immunization methods on the body is different. Take the first immunization as an example, eye and nose drops should be used during the first immunization of Newcastle disease. The important purpose of the first immunization is to break through maternal antibodies and stimulate the body to produce basic immunity. Eye drops and nasal drops are mainly through Hade's gland, which can avoid the interference of maternal antibodies, while Harder's gland is behind the eyes, so Newcastle disease should be first exempted from eye and nose drops. Bursa of Fabricius should be given by dripping or drinking water; avian influenza must be injected intramuscularly; Ⅰ vaccine should be injected intramuscularly in the later stage of immunization of laying hens. It should be noted that it is best to use a special diluent when diluting the vaccine, and it is best to use cold boiled water when you point your eyes, nose, mouth or drinking water. it is forbidden to contain disinfectant in the diluent or to hold the diluted vaccine in a metal container. otherwise, there will be immune failure or immune damage. now many chicken farmers think that the larger the amount of vaccine, the better, which is also wrong, the vaccine dosage is too small or not used for a long time, the immune effect can not be achieved. Too much vaccine or too frequent immunization can cause paralysis of immune organs, so the bigger the vaccine, the better. Take Newcastle disease as an example: during the laying period, it is best to drink 4 times 5 times of C030 or Ⅳ vaccine every other month to one and a half months, while adding some immune enhancers (such as astragalus polysaccharides).

(5) interference between vaccines. When two or more non-cross-reactive vaccines are vaccinated at the same time, the immune response of one of the vaccines will often be reduced, affecting the immune effect, such as Newcastle disease and bursa of Fabricius, throat transmission and Newcastle disease, etc. this will lead to immune failure, so the immune interval between the two is at least seven days.

(6) the reasons of feeding and management. Stress factors such as too cold or overheat, high humidity, poor ventilation, crowding, feed mutation, conversion, beak breakage and other stress factors will lead to the increase of adrenocortical hormone secretion, while adrenocortical hormone can significantly damage lymphocytes. It can inhibit macrophages and increase the catabolism of immunoglobulin, so the stress of chicken flock is reduced as much as possible before and after immunization, and some immune enhancers are added at the same time. Vitamins, trace elements and total protein can affect the immune response of the body to antigen. For example, amino acids can increase the content of immunoglobulin. It is reported that the addition of a certain amount of arginine to the feed can significantly promote the growth of chicken lymphoid organs and effectively improve the immune response; on the contrary, the lack of arginine will reduce the weight of immune organs and cause immune damage. in addition, vitamin A deficiency can lead to premature atrophy of bursa of Fabricius and decrease of resistance, so various nutrients should be supplemented to ensure the normal development of immune organs. There is usually not thorough disinfection, the environment contains a large number of pathogenic bacteria, the use of vaccine during the chicken flock in a state of sub-health. Especially during the summer Meiyu period, the moisture in the feed exceeds the standard, and sometimes how much the feed is matched will inevitably become moldy. Aflatoxin causes atrophy of the immune organs of the body (such as bursa of Fabricius, thymus, etc.), which will lead to damage to the immune system, resulting in immune failure. Therefore, it is necessary to strengthen the work of disinfection and sterilization at ordinary times to prevent feed mildew and make the chickens in a healthy state during immunization, so as to improve the immune effect and prevent the occurrence of diseases. Increase the benefit of raising chickens.