Chicken farmers should understand the process by which chickens develop from cold stress to wind-cold illness.
Recently, the most common issue I have encountered has been respiratory diseases in flocks. Once respiratory symptoms occur in a flock, the illness is difficult to control. The flock’s feed intake does not increase, and it is also very costly for farmers to manage. Therefore, I will provide a detailed overview of comprehensive prevention and control measures for respiratory diseases in flocks in recent times.
Causes of illness in the flock:
The main reason for the recent high incidence of disease in flocks is related to the season. At this time of year, there is a large temperature difference between day and night, as well as a large temperature difference between inside and outside the poultry house, making it very difficult for farmers to ventilate their poultry houses. If they are not careful, their flocks may suffer cold stress, which can then lead to a series of problems. To address these problems, farmers need to understand in detail the changes that occur in chickens after they experience cold stress so that they can provide more targeted treatment.
The disease process in a flock:
Respiratory symptoms in a flock develop over time. Chickens do not suddenly develop problems such as colds, high fever, or death; these occur step by step.
1, Formation of cold stress
First, poultry farmers may be negligent in their management, allowing cold air and other conditions to affect the flock. The chickens are exposed to a “cold” stimulus, triggering a stress response. At this point, the flock may show abnormal reactions, with a brief increase in water intake and feed consumption. This is because after exposure to cold, the flock may develop mild symptoms of fever, accompanied by an increased thirst, causing an abnormal rise in water intake and feed consumption. This is one indicator of whether the flock is experiencing cold stress. If the weather suddenly turns colder and the flock’s feed consumption increases abnormally, the poultry farmer should take this seriously: the flock is already experiencing cold stress. At this point, the poultry farmer can use Xiao Chai Hu San or ginger and brown sugar water. At the same time, during this stage, the poultry house temperature must be raised by 1~2 degrees Celsius to effectively alleviate cold stress in the flock.
2, The onset of a cold
The cold-stress process is very brief. Many poultry farmers lack experience and have no time to notice it before the disease progresses to the next stage, developing into a cold. After chickens experience cold stress, their capillaries constrict. At this point, the blood supply to mucous membrane areas such as the larynx and eyelids becomes inadequate, reducing these areas’ ability to resist external pathogens and leading to early cold symptoms. The chickens may develop a clear runny nose, their eyelids may become congested, and their eyes may become watery.
3, the appearance of the H9 virus
When chickens catch a cold, the illness continues to progress, the flock develops a fever, and resistance declines further. At this point, the H9 virus at the poultry farm will take advantage of the situation. Many poultry farmers are now puzzled about colds in chickens: what exactly is the difference between a cold and the flu?
Mild H9 flu is actually a normal occurrence, and it can be detected directly at the vast majority of poultry farms. However, the H9 virus itself has a very low fatality rate, and the H9 virus alone does not pose much of a threat to the flock. Under normal circumstances, the chickens’ tracheal mucosa is intact and their own resistance is strong enough, so these viruses cannot cause them any harm. But when chickens get chilled and catch a cold, their resistance declines, and the H9 virus and diseases such as mycoplasma in the chickens’ bodies begin to break out.
4, Formation of tracheal inflammation
When infection with the H9 virus, mycoplasma, colds, and other agents occurs concurrently, respiratory symptoms in the flock develop rapidly, with severe coughing in many chickens. At this point, the chickens’ tracheas become damaged, with diffuse bleeding in the trachea. Once the tracheal mucosa is damaged, the gateway to the chickens’ respiratory system is completely opened. E. coli, staphylococci, streptococci, mycoplasma, dust, and other agents in the air then begin to colonize the trachea and multiply in large numbers, leading to inflammation.
5, formation of pneumonia
The H9 virus then moves downward and attacks the chicken’s lungs, with various pathogens following it. The chicken may develop symptoms such as pulmonary edema, lung congestion, and lung necrosis. At this point, sporadic cases of chickens stretching their necks to breathe may occur. This indicates that the lungs have already been damaged. During dissection, mucus or yellow caseous material may be found in a small number of chicken lungs.
6, formation of airsacculitis.
The chicken’s lungs and air sacs are connected. Once the chicken’s thoracic air sacs are infected, the abdominal air sacs can soon become infected as well, resulting in peritonitis. When peritonitis occurs, Escherichia coli begins to proliferate extensively. These fibrinous exudates begin to cause symptoms affecting the liver, then spread upward and form pericarditis. During reproduction, Escherichia coli produces large amounts of endotoxin. At this point, the chicken may develop septicemia, leading to widespread deaths.
Summary:
The progression of this viral cold develops from top to bottom. Therefore, farmers can clearly understand the severity of the disease in the flock by following this sequence. In the early stages, the main symptoms are inflammatory reactions such as airsacculitis. These inflammations reduce the chickens’ feed intake but do not cause mortality.
Once airsacculitis, peritonitis, and other conditions have developed, Escherichia coli can break out and endotoxins can accumulate in the chickens’ bodies, leading to an increase in mortality. Therefore, when preventing and controlling the problems that follow chickens getting chilled and catching a cold, farmers should not panic. With proper control, addressing both H9 virus and Escherichia coli can effectively control the disease and losses in the flock.