At present, the main diseases affecting the health and production performance of laying hens are MS, AE, IC, ILT, IB, H9, etc. But in terms of the economic loss of the farm, IB should be in the first place. In particular, the chickens from April to June 2017 were deeply infected with IB.

1、 Study on the causes of the disease

Everyone is familiar with the disease of IB. IBV is a multi serotype virus. The main route of infection is the respiratory system, mainly affecting the respiratory system, reproductive system, urinary system, etc. At present, QX strain is the main epidemic strain. We also use a wide range of vaccines in China, including live and inactivated vaccines. The most commonly used are mass type: Ma5, H120, 28 / 86, H52, W93; 4 / 91 type: 4 / 91; Ldt3 / 03: ldt3-a; QX type: qxl87; Inactivated vaccine M41 and so on.

Persistent respiratory diseases and recurrent respiratory diseases are the main causes of IB infection. These two diseases make the respiratory tract mucosa of chickens damaged repeatedly.

As we all know, the protection of IB mainly depends on mucosal antibody, and the main route of infection is respiratory system. Continuous or repeated mucosal damage results in the decrease of immune protection rate of IB vaccine made during chicken and breeding period, which leads to the infection of IBV.

In particular, the high incidence areas of this disease are the young chicken farms which continuously enter the chicken, which are not all in and out of the chicken, which are not empty and hardly empty when the market is good, the polyculture farms of different age chicken groups, and the newly put into use breeding farms with high degree of automation.

So what causes persistent respiratory diseases and recurrent respiratory diseases in brooding and growing period? What are the symptoms and how to prevent them?

First, wind cold stress

Cause of disease

Excessive ventilation, temperature controller problem, air inlet too close to chicken, negative pressure value is not enough, wind direction has turn back, chicken house is not closed tightly, there is thief wind, etc.

Clinical symptoms

All of a sudden, the mental state of the chickens became worse, daily consumption of food decreased, drinking water decreased, their necks were withered, their feathers were coarse and disordered, one or both nasal cavities were clear, and they sneezed and coughed at auscultation at night. If not timely prevention and treatment, it will be secondary infection with other pathogens.

Prevention and control measures

Choose the time of the lowest temperature in the day, feel the temperature change near the sick chickens, look for the source of cold wind, find the root cause, and solve it thoroughly.

If the incidence rate is less than 1% of the population, the chickens will recover naturally after adjusting the ventilation. If it is found later and the incidence rate is more than 1% of the population, we should take tylosin, doxycycline, Shuanghuanglian and other drugs for prevention and treatment according to the needs of the disease.

Second, small ventilation, ammonia and other harmful gases exceed the standard

Cause of disease

In order to keep warm, the air exchange rate is too small, and the harmful gas in the henhouse is not discharged in time. In addition, the abnormal fermentation of chicken manure caused by untimely defecation and water leakage of drinking nipple is also a reason for the disease.

Clinical symptoms

The eyes of the chickens were deformed, dormant and lacrimal, and the eyelids were red and swollen, especially in the upper layer or exhaust outlet. A few chickens coughed and snored. When people leave, the chickens like to lie down. When people come over, the chickens are in a better mental state. There is no obvious change in feeding and drinking water.

Prevention and control measures

According to the minimum respiratory rate standard, the ventilation rate was determined. When the heat preservation and minimum respiratory rate conflict, the heat preservation was ignored to ensure the minimum respiratory rate.

In order to increase the temperature of chicken house, we should consider the airtight and heat preservation of chicken house. Timely replacement of leaking nipples, timely adjustment of water line height, to prevent water leakage due to chicken touch.

Clean up the faeces of chicken house in time to prevent harmful gas produced by faeces fermentation.

Third, negative pressure, hypoxia

Cause of disease

The closed henhouse has large exhaust air volume and small air inlet, which causes the negative pressure of henhouse to exceed the standard for a long time and the chickens to lack oxygen for a long time.

Clinical symptoms

There was no abnormal performance in the chickens. More chickens were auscultated for respiratory rales at night, especially for wet rales. The number of dead chickens increased. Congestion and necrosis occurred in one lung of the dead chickens. Occasionally, cheese blockage occurred in trachea and bronchus.

Prevention and control measures

The negative pressure can be adjusted to a reasonable range by using frequency converter to reduce the exhaust air volume of fan or increase the area of air inlet. The chickens with serious disease were treated with doxycycline and neomycin.

Fourth, high temperature and low humidity

Cause of disease

Due to the particularity of the anatomical structure of the respiratory system of chickens, in addition to the exchange of oxygen and carbon dioxide, the respiration of chickens also undertakes the main heat dissipation function. Therefore, in the environment of high temperature and low humidity, the respiratory system of chickens is more urgent, and the respiratory tract mucosa is vulnerable to damage, resulting in the occurrence of respiratory diseases.

Clinical symptoms

The chickens showed dyspnea, neck extension, mouth opening, head shaking and other symptoms. At night, the chickens had cough, screaming, snoring and other pathological respiratory sounds. The trachea of the dead chickens was congested, and only trachea and bronchus embolism occurred in some chickens.

Prevention and control measures

When the temperature is suitable, pay attention to increase the humidity in the air of the henhouse, especially during the period of chickling, the appropriate humidity is one of the necessary conditions for the health of chickens. Sensitive antibiotics such as enrofloxacin, doxycycline and expectorant antitussive drugs for prevention and treatment.

Fifthly, the sanitary condition of chicken house is poor, and the dust exceeds the standard seriously

Cause of disease

In winter, the exhaust air volume of the chicken house becomes smaller, the chicken house is not hygienic, and the dust in the air seriously exceeds the standard.

Clinical symptoms

Chickens sneeze, cough, and snore severely. After entering the chicken house, you can see the dust floating in the air. A few minutes later, people’s clothes and hair are all white dust. The respiratory diseases of the chickens are not cured for a long time.

Prevention and control measures

When the temperature is allowed, the exhaust air volume should be increased to discharge the dust from the henhouse. In addition, timely cleaning of chicken house, humidification and dust reduction are good methods to remove dust. Serious with tylosin, Shuanghuanglian and other prevention and treatment.