Epidemic trend and prevention and control of infectious bronchitis
Release time:
Jun 14,2018
The current epidemic strains, mainly prevalent in China endemic to the main nephrotropic strains, representative strains including QX, A2, LX4. A small number of M-type strains with respiratory manifestations still occur.
The main hazards of infectious bronchitis are reflected in five aspects:
The chicks were susceptible within 10 weeks of age, and the severity decreased with the increase of age. In addition to severe damage to the respiratory and urinary tracts, infected chicks also showed different mortality rates depending on the type of epidemic strain. The mortality rate of kidney-type epidemic strain infection is mostly 15% ~ 30%, or even higher, and the course of disease lasts 7~10 days. Age resistance, reduced after 8 weeks.
Chick infection will lead to the absence of egg production peak of laying hens, the higher the infection, the lower the peak of preterm eggs. Clinically accompanied by a large number of false hens (non-laying) and large-bellied chickens with hydronephrosis.
Adult laying hens rarely develop the disease under current immunization conditions. If the immune failure and no resistance of laying hens infection will appear serious egg production decline, lasting up to 40 to 60 days, egg quality is very poor, egg white water-like change.
Poor immunity leads to infection of laying hens with uneven antibody levels, with different manifestations, common transient respiratory symptoms, slight decline in egg production, and poor egg shell and egg quality. There is a clear contagion process.
For the diagnosis of the disease, in addition to the above-mentioned typical clinical symptoms, chicks also showed increased death, discharge of white loose feces, autopsy more see spotted kidney. There is no peak in laying hens, and fake hens and big-bellied water chickens appear. The peak value of laying eggs can generally determine when IB is infected. ELASA detection of abnormally high antibody levels, mainly for the first few weeks of breeding chickens, combined with medical history has a certain diagnostic value. For large chickens and laying hens with no clinical abnormalities, it can only indicate a wild virus infection. At the same time, PCR sequencing and virus isolation were used to further confirm the diagnosis.
In the setting of its immunization program, H120 live seedlings (kidney type live seedlings and 4/91 live seedlings) are generally immunized for 1-3 days. For 10-14 days, use kidney type live seedlings or 4/91 live seedlings, 20 days left ancient: use H120 live seedlings (add kidney type live seedlings or 4/91 live seedlings); Prenatal: kidney type or 4/91 inactivated vaccine, M type inactivated vaccine. At other times, the actual situation in the breeding process may require increased immunity.
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