1. Vaccine issues
The storage and transportation of vaccines directly affect the quality of vaccines, and is also a key factor for the success of immunization. If the temperature is not well controlled during storage and transportation, the immune effect of the vaccine will be reduced. Outdated vaccines must not be used. When purchasing vaccines, regular manufacturers should be selected to ensure the quality of vaccines and not be greedy for cheap. Selection of vaccines suitable for serotype preparation in the region, some newly marketed vaccines are often targeted, prepared according to the current epidemic situation, and can be recommended by veterinarians.
2. Choice of immune pathway
The immune pathways include nose dropping, eye dropping, mouth dropping, drinking water, seed pricking, injection and aerosol immunization. No matter how good the vaccine is, the incorrect immune pathway may also cause immune failure. For example, drinking water immunization has the advantage of saving time and labor for mass immunization, but the disadvantage is that the immune dose of each chicken is not accurate, and some of them drink less water and may not reach the immune dose. Vaccines are rarely found in the eyes and nose and do not produce antibodies locally in the respiratory tract. So the first immunization is best by nose drops and eye drops. Bursa of Fabricius Immunization Drops, Drinking Water Immunization does not generally do initial immunization. Drinking water is an alternative to boosting immunity after the second time. Newcastle disease IV, infectious bronchitis and so on adopt nose dropping and eye dropping. Antigen can enter the body through nasal and eye mucosa. Mucosal inoculation can quickly enter the lymphatic circulation system. After eye dropping, the vaccine antigen directly stimulates the disseminated lymphoid tissue in the Hard's gland and subconjunctiva of the fundus of the eye, thus forming a solid local barrier.
3. Use of vaccines
Nose drops and eye drops. During immunization, to ensure that the vaccine enters the eyes and nasal cavity, chickens are thrown away after dripping. Often, the vaccine droplets also drop, and must be absorbed.
Drinking water immunity. To finish drinking as soon as possible, stop drinking water beforehand, stop drinking water for 2-3 hours in winter and 1-2 hours in summer, it is better to finish drinking vaccine water within th. In order to ensure water quality, tap water containing disinfectants such as bleaching powder and water containing metal ions should not be used, nor metal water dispensers should be used. Water with high salt and alkali content should be boiled and cooled, then the vaccine should be diluted after removing impurities and precipitation. When infectious bursal disease vaccine is immunized, 1% - 2% skim milk powder is added to drinking water to protect the vaccine. Vaccines for injection should be added after one bottle, not all at once, otherwise the immune potency will decrease if they are placed for too long, especially in large flocks of chicken farms, sometimes they can not be injected in a day.
Aerosol immunization, often with stress response, is generally less used, often causing respiratory tract infections. The stress response caused by aerosol is inversely proportional to the size of aerosol particles. Hence, chickens with a history of respiratory diseases are more suitable for aerosol immunization with larger aerosol droplets.
Needle seeds, often used for chicken pox, inoculated under the wings, 3-4 days after seed pricking, the site of seed pricking is swollen, blisters and scabs, 2-3 days crust shedding shows that immunization success, otherwise need to be replanted, especially in areas where chicken pox occurs frequently, often due to immune failure.
4. Irrational Immunization
The immune dose is too high. Some farmers blindly increase the dosage or frequent immunization, sometimes resulting in immunosuppression or neutralization of vaccine antigens and immune antibodies in vivo, resulting in the occurrence of diseases. Especially, the immunization of Newcastle disease is unreasonable, and atypical Newcastle disease often occurs.
The effect of drug interference on immunity is universal. Especially when using live vaccine, antibiotics can not be used for 5 days before and after immunization. The acidity and alkalinity of some drugs and most antibiotics exist in the form of salts. Although antibiotics are ineffective against viruses, these containing acids, bases and salts can also destroy the immune effect of the vaccine. Long-term use of excessive antibiotics, especially streptomycin, kanamycin and gentamicin, can destroy chicken leukocytes and lymphocytes and affect the production of immune antibodies.
Interference between different vaccines. Some vaccines interact with each other or interfere with each other, and should not be used simultaneously or in the near future. Unless two-seedling and three-seedling are used, farmers should not mix them unauthorized.
The immunization procedure is unreasonable. Different vaccines maintain antibodies in animals for different periods of time. If chickens have been injected with oil vaccine of Newcastle disease before birth, they will be vaccinated once again after 50-60 days, and start immunization together. Some farmers think that the more the vaccination times, the better, they will be immunized once a month, resulting in immune paralysis or neutralizing antibody titer, which is easy to cause disease.
5. Interference of maternal antibodies
Breeding chickens are immunized before birth, some of their own antibodies will be transmitted to the next generation, which has a certain protective effect on disease resistance of chickens. However, in the course of vaccination, maternal antibodies and vaccine antigens neutralize, resulting in immunization failure. Therefore, chickens should be monitored to determine the first immunization time according to the titer of maternal antibodies.
6. The influence of chicken auto-factors on immunity
There are some diseases in the body, such as coccidiosis, infectious bursal disease, Marek, Newcastle disease, adenovirus, infectious anemia factor and so on, which can cause immunosuppression or reduce the level of immunity. Nutrition deficiency: Poor health of chickens, body weight loss, malnutrition, vitamin deficiency, can not produce enough antibodies and lead to immune failure. Stress factors: Chicken flocks before and after immunization are in a strong stress period, such as disease, sudden cold, extreme heat, feeding restriction, transfer, beak breakage, high density, poor ventilation and other vaccination recovery period, which can weaken the immune response ability, but also make the body immune antibody decline sharply, and also affect the immune effect again.
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