In broiler chicken breeding, if this disease cannot be prevented, sporadic deaths will continue until they are out!

In Broiler Chicken Breeding,
if this Disease cannot be Prevented,
Sporadic Deaths will continue until they are out!

Atypical bursitis was found in broiler chickens aged more than 10 and 20 days old in several major broiler chicken breeding areas in Shandong, China. The reason why it is not called bursitis is because when it is diagnosed by veterinarians in daily clinical diagnosis, the main clinical symptoms of bursitis are atypical and difficult to diagnose as bursitis. However, for this kind of broiler chickens with prominent necropsy symptoms such as kidney redness and swelling, kidney bleeding, kidney congestion, kidney atrophy, and clumps of kidneys, the report result of collecting the patient materials and submitting them for examination and testing was "positive for the bursa of Fabricius."

In the past era when bursitis was rampant, everyone recognized it as infectious bursitis disease in chickens, which is a highly contagious contact and acute infectious disease. With the improvement of the breeding model and the improvement of feeding and management technology, it seems that the frequency of bursitis has decreased in recent years, resulting in people not paying much attention to preventing and controlling this disease during breeding and production. In fact, the incidence of bursitis in chickens has always been high. According to the analysis of continuous monitoring data from front-line breeding farms, the detection rate of bursitis is increasing year-on-year.

The reason why everyone doesn't care about it, or in other words, everyone turns a blind eye to the ongoing bursitis in broilers, is because the bursitis virus causing the disease is a new "mutated strain". The clinical symptoms caused by it infecting chickens are different from those caused by classic strains in the past. In other words, the bursitis that is currently occurring in broiler chickens is caused by the mutant strain and has "atypical symptoms". People do not recognize it and assume it does not exist. Daily epidemic prevention and diagnosis do not pay attention to the disease. It all starts with the classification of chicken bursal disease and the characteristics of current popular strains.

By using polyclonal antibodies and cross-neutralization experiments with viruses, chicken infectious bursal virus isolates were serotyped and can be mainly divided into serum I and serum II. Since serotype II viruses are not virulent, we often talk about serotype 1 bursal virus. According to the antigenic characteristics and pathogenicity of bursal virus, serotype I can be divided into three types: classic strain, super virulent strain and mutant strain (some people also take the vaccine strain of attenuated strain into consideration, so there are four kinds of poison beads). According to the monitoring and analysis of daily collection of disease materials from front-line chicken farms, most of the strains of bursitis virus currently prevalent in China are mutant strains.

People who are familiar with bursitis know that traditional/classic bursitis has typical clinically diagnosed lesions and symptoms such as leg muscle bleeding and massive bleeding like purple grapes. The super-strong bursitis virus strain can also cause pathological changes such as spotted kidney and glandular gastric hemorrhage in chickens. According to epidemiological survey reports, the fatality rate of classic bursal virus disease ranges from 10% to 50%. The fatality rate of super-strong bursal disease is 50%-100%. As for the variant bursitis that currently occurs clinically in broiler chickens, the fatality rate of simple infection is basically 0. The main problem is that infected chickens grow slowly and are prone to colds.

Because the mutant strain causes damage to the bursa of Fabricius, the central immune organ, leading to severe immunosuppression, resulting in problems such as poor growth and development of chickens, increased feed ratio, and reduced production performance, detection can only detect it. In addition, mutated bursal virus infection not only has the above hazards; some studies have confirmed that it can also cause the immune titers of Newcastle disease and influenza vaccines to drop by at least 2 titers, and chickens are also susceptible to infectious diseases due to immunosuppression, such as Chronic larynx, Marek's disease and many other diseases.To prevent and control this chicken disease, the first step is to be immunized. The prerequisite for good immunization is to choose a good vaccine and integrate vaccination and prevention with vaccination.

Secondly, terminal disinfection and daily disinfection between batches are the most economical and efficient way to prevent atypical bursitis in large-scale broiler farms. Bursal virus is very stable and resistant to acid, alkali, certain disinfectants and high temperatures. Inactivation begins at pH 12 (certain alkali resistance). Viruses at pH 2 (acid resistance) are not affected and have a certain tolerance to general disinfectants. It can also withstand certain high temperatures. Third, improve the immunity and anti-stress ability of chicks; fourth, strengthen daily cold stress management. Many disease-causing chicken flocks or chicken farms are triggered by sudden high and low temperatures.