Causes and Control Countermeasures of immune failure in Chicken Farm

Xinye County in recent years,@#@230@#@industry momentum is strong, small and medium-sized chicken farms mushroomed, vigorous development. With the rapid increase of breeding industry, how to do a good job of chicken herd immunization has become urgent, most farmers can also realize the importance of epidemic prevention work, but due to various reasons, the immunization effect is not accurate and futile, and the economic benefit obviously declines. According to many years of practical experience, the author put forward some superficial views on the reasons of chicken farm immune failure, for the reference of the vast number of breeding peers.

1 Reasons for immune failure

1.1 In recent years, due to the widespread use of various vaccines for breeding birds, the maternal antibody level of chicks has been significantly improved. If the maternal antibody level is high, the vaccine antigen is neutralized by maternal antibody, which makes it impossible to proliferate in vivo. This results in immune failure, and also reduces the level of maternal antibody, thus increasing the susceptibility of chicks. Once there is a virulent virus invasion, diseases may occur.

1.2 The quality of vaccine should meet the standard. The key of attenuated vaccine is vitality, and the key of live vaccine is effective content. Attention should also be paid to the transportation, preservation and validity period of vaccine. Otherwise, the vitality titer of vaccine may be reduced, resulting in immune failure.

1.3 Inoculation method is not appropriate all kinds of vaccine have certain inoculation method, if dot eye, drinking water, aerosol, inject, thorn seed to wait. Chicken vaccine should be used puncture seed method inoculation, such as drinking water, eye method can not achieve due effect.

1.4 Mishandling of vaccination vaccine diluent contains vaccine-destroying substances (Iron, chloride ions, disinfectants, etc.) or add antibacterial drugs, arbitrarily increase or reduce the dilution concentration and cause vaccine excess or deficiency; dilution of the vaccine does not pay attention to time and place, all day in the sun, so that the vaccine in the high temperature environment invalid; drinking water immunization can not be completed within the specified time or drinking water is not neat, such as Marek's disease vaccine diluent to be injected within 1~2 hours, the rest of the vaccine to vaccinate chickens will occur immune failure.

1.5 Improper combination of vaccines Some vaccines can be used in combination, some will interfere, if the combination is improper or the time interval between two vaccines is too short, it will also cause immune failure. For example, Fowlpox vaccine and Newcastle vaccine interfere with each other and infectious bronchitis virus interferes with Newcastle disease virus.

1.6 Infectious diseases interfere with infectious virus can kill B lymphocytes in bursa of Fabricius, so that antibody generation disorders occur, so bursa of Fabricius disease often causes immune failure of other diseases.

1.7 Immunization blank period by pathogen infection any vaccine from vaccination to chicken immunity in vivo need time, this period of time called immunization blank period. Infection during the blanking period can still cause disease.

1.8 The immune degree is unreasonable different chicken flocks, the antibody level is also inconsistent. Immunization time is first and then, different nature of the vaccine, immunization methods are also different, which requires the establishment of reasonable immunization procedures, unreasonable degree of immunity is easy to lead to immune failure.

2.1 Formulate reasonable and feasible immunization procedures Due to different local conditions (epidemic situation, chicken breed, chicken seedling source, etc.), it is impossible to have a fixed immunization procedure, so each chicken farm should formulate an immunization procedure suitable for the actual chicken farm according to the epidemic situation of chicken disease and local epidemic situation, combined with the fluctuation law of antibodies produced by various vaccines (immune antibody monitoring). For example, if chicken Newcastle disease is used for basic immunization, if chicken seedlings from regular breeding farms, such as many native chickens and local chickens from scattered households and farmers, and not necessarily from the same farm owner, the maternal antibody of chicken seedlings will be very low or even absent, so basic immunization of Newcastle disease should be carried out on the first day.

2.2 Reduce stress reaction In the process of vaccine immunization, various stress reactions should be minimized, and it is not advisable to perform beak cutting, group transfer, refueling and other work at the same time. After vaccination, feeding management should be strengthened. Adverse factors such as too low temperature of chicken house, crowded chicken flock and poor ventilation will inhibit humoral immunity and cellular immunity of the body, resulting in decreased protection of vaccine. In order to reduce the stress response of chickens during vaccination, vitamin C, vitamin K or immune enhancers can be added to drinking water 2 to 3 days before and after vaccination, or reserpine, chlorpromazine and other anti-stress drugs can be added to feed.

2.3 Use correct immunization operation method and inoculation route The commonly used inoculation methods include nose drop eye method, drinking water immunization method and injection method, which should be inoculated according to the prescribed method and cannot be changed at will.① Eye drop nose drop method. This is a common way of immunization for chicks. When using this method for immunization, you must see that the vaccine completely enters the eye or nose before releasing it. Do not release it immediately after dripping, so as to avoid the vaccine flowing out from the eye or nose and affecting the immune effect. 2. Drinking water immunization method. It is best to use deep well water, tap water should be placed overnight before use; drinking utensils must be cleaned; vaccine dosage should not be excessively increased, otherwise it will cause strong stress and affect immune effect. The amount of diluted vaccine should be appropriate, and it is appropriate for chickens to drink it within 30 minutes.③ Injection method. The injection method and diluent should be used according to the instructions. Malick vaccine must be diluted with a special diluent provided by the manufacturer, and general vaccines are diluted with sterile water for injection.

2.4 The effect of vaccination depends on whether the immune system functions normally. Therefore, all diseases that damage immune organs, such as chicken infectious bursal disease, should be effectively prevented. At the same time, it is also necessary to prevent moldy feed, because the mycotoxins contained in moldy feed will destroy the normal function of the immune system and form serious immunosuppression. In addition, because it takes about 7 days to vaccinate attenuated vaccine and about 15 days for oil emulsion inactivated vaccine to produce strong immunity, in addition, different vaccines have different antigenicity, so do not be careless after vaccination, strengthen isolation and disinfection work, isolate and raise immunized chickens for more than 15 days, at the same time, strictly disinfect personnel entering and leaving chicken houses, and prohibit outsiders from entering chicken houses.

2.5 The all-in and all-out system shall be adopted as far as possible. After each batch of chickens is released, a comprehensive and thorough cleaning and disinfection shall be carried out to prevent the retention and spread of pathogens.