As the weather gradually warms, the incidence of infectious bursal disease in native chickens gradually increases, especially during the wheat harvest season, when the incidence reaches its peak. Infectious bursitis is an acute, highly exposed infectious disease caused by the bursitis virus. Therefore, both native chickens and broilers are very susceptible, and their susceptibility is related to the stage of bursal development of chickens.
The disease mainly affects native chickens under 3 months of age, especially 2 to 5 weeks old native chickens are more likely to be infected with the disease, while adult native chickens that have degenerated bursa are only negative infections. If the disease occurs in the native chicken, if it is not treated in time, the incidence rate is more than 70%, and the case fatality rate is about 30%, which shows that the infectious bursal disease of chickens is a very contagious disease, so it is also very important for farmers to prevent and control the occurrence of the disease. So in the process of native chicken breeding, how does infectious bursal disease in chickens occur, and how to prevent the disease? Plum to talk about.
The author received a case a few days ago, a farmer in a neighboring village purchased 1,000 native chickens for free range, he used the ground level, bedding brood brooding at that time. At the age of 15, the native chicken flock used chicken infectious bursal disease vaccine for drinking water, but at about 30 days, the native chicken flock suddenly fell ill and quickly affected the entire flock. After the onset of the disease, the native chicken reaches a peak of death on day 4, with about 10% of deaths.
Although farmers are treated with general antiviral drugs and antibiotics, their economic losses are still relatively serious because farmers have not paid attention to them at first. Therefore, once the native chicken has symptoms of bursal disease, it is necessary to take early treatment measures to control it.
The disease is only affected by chicken infections, which include chickens such as native chickens, broilers and layer chickens, and generally have the highest incidence in spring and summer, which is related to the temperature environment and humidity in spring and summer. Infectious bursal disease mainly affects chicks, 2 to 15 weeks old is susceptible to infection, and the main source of infection is sick chickens and negative infected chickens, its mode of transmission is highly contact transmission, through the respiratory tract, digestive tract, eye conjunctiva can be infected. After the occurrence of this disease, often secondary to coccidiosis and E. coli disease, due to the widespread use of infectious bursal disease vaccine, the infectivity of native chickens has gradually changed to a mild type.
The incubation period of this disease is 2 to 3 days, the course of the disease is about 1 week, and the mortality rate of chickens with typical infectious bursitis is relatively high, and its death curve is peaked. In the early stages of the disease in sick chickens, some sick chickens peck their anus, which may be due to the pain and itching of the bursa. Illness and loss of appetite, increased water intake.
However, with the development of the disease course, the sick chicken is highly depressed, the head is shrunk, and the body temperature rises, of which the lime water-like thin stool of the sick chicken is the main feature, and the chicken feet are dehydrated and dry. Acutely ill chickens die after 1 to 2 days after symptoms, and most of the native chicken flocks reach a peak of death in 3 to 5 days, and then gradually decrease.
Through the dissection of sick and dead native chickens, it was found that the bursitis virus mainly affected the bursal sac.
Symptoms at the beginning of the disease: the initial bursa swollen, usually on the fourth day after the onset of the disease to the maximum, about 2 times the original. At the same time of swelling, there is a yellowish gelatinous exudate on the outside of the bursa, longitudinal streaks become apparent, and the mucous membranes in the bursa are edematous, hyperemic, hemorrhagic, and necrotic. The bursa cavities contain creamy or brown jam-like exudates.
Late onset: In some cases of later stages, the bursa is heavily bleeding, its appearance is purple-black, brittle, and the bursal cavity is filled with blood clots. On the fifth day after the onset of the disease, the bursa began to atrophy, and after the eighth day, it was only about 1/3 of the original. After contraction, the mucous membrane loses its luster, is drier, grayish-white or earthy yellow, and most of the exudate disappears.
Other anatomical findings: patchy bleeding spots in the pectoral and leg muscles, pale muscle color. The glandular gastric mucosa is hyperemic and flushed, and the mucous membrane at the junction between the glandular stomach and the muscle and stomach has bleeding spots, which are arranged slightly banded, but the glandular gastric nipples have no bleeding spots.
1) Immunization:
Immunization time: When the native chicken is immunized, it must be selected according to the type, nature, age of the chicken, feeding management and other conditions of the vaccine. If possible, native flocks can be monitored according to agar diffusion experiments to facilitate the selection of an appropriate immunization time. If the farm is not conditional, the usual immunization procedure for bursitis can be followed. For example, when vaccinated, the first exemption is carried out at the age of 12 to 14 days of the native chicken, and the immunization method is drip or drink water. At the age of 28 days of the native chicken (if the local bursitis is more severe, it can be carried out earlier to 21 days old), and the immunization method is 3 times the amount of water.
Choice of bursal vaccine: When choosing a vaccine, it is also necessary to follow a reasonable vaccine, generally speaking, the vaccine of the medium strain of bursal sac has a certain damage to the chicken, but only the medium strain of the bursal vaccine can have an immune effect on the chicken. Therefore, when immunizing the chickens, you can choose a vaccine with a medium strain, but in order to improve the immune effect, you can drink astragalus polysaccharide oral solution 2 to 3 days after giving the chicken immunization.
Precautions: When vaccinating the native chickens against the bursa, it is necessary to be reasonably immunized according to the local prevalence of the bursa, especially in the season and endemic area of the high incidence of bursa, and must be strictly immunized in accordance with the requirements of epidemic prevention.
2) Do a good job in the hygiene of the native chicken herd:
All breeding practices have proved that only by doing a good job in the hygiene of the native chicken flock can we effectively prevent the occurrence of bursitis of the native chicken, so when breeding the native chicken, we must carry out strict hygiene management and strengthen disinfection and purification measures. The operation method is as follows: before entering the chicken, spray the chicken coop with disinfectant and clean the chicken coop, and then use a variety of disinfectant to alternately disinfect the chicken coop without leaving a dead corner. During the raising of native chickens, regular aerosol disinfection of native chickens and the clear feces in the chicken coop at any time can effectively prevent the occurrence of infectious bursitis in chickens.
environmental management:
First of all, when treating, we must do a good job in the environment of the chicken coop. Therefore, during the treatment period, we must first increase the house temperature of the native chicken, so that the local chicken is in a relatively warm environment, and the increase in the house temperature is better at 1 ~ 2 ° C. And add electrolytic multidimensional to drinking water to maintain the water and nutrient balance of the chicken body, which is conducive to promoting the rapid recovery of the native chicken.
The sick flock should be strictly sealed, and the chickens with more serious diseases should be picked out in time and treated separately. Chickens are disinfected once a day in the morning and afternoon, and the environment, personnel, and tools are also disinfected.
drug therapy:
If the native chicken has bursitis, it must be treated as soon as possible, so as to avoid a large loss of the native chicken. At the time of treatment, the chickens are injected with high-immune serum or yolk antibodies, and death can be controlled one day after the injection. However, some native chickens still have the disease after injecting yolk antibodies for 1 to 3 days, so it is necessary to use some good quality yolk antibodies for cure, and at the same time as injecting yolk antibodies, with drugs for treatment, you can put an end to the secondary onset of the native chicken flock, and the treatment phenomenon is not obvious.
When injecting turkeys, chicks inject 0.5 to 1.0 ml, large chickens inject 1.0 to 2.0 ml, subcutaneous injection or intramuscular injection when injecting, and re-inject again the next day when necessary to consolidate the purpose of treatment.
Notes:
When injecting egg yolk antibodies into turkeys, we must choose good quality yolk antibodies, generally regular veterinary drug companies are OK, in order to avoid cross-infection of turkey injections, when injecting, we must spare injection needles, and disinfect the needles, while adding an appropriate amount of antibiotics to each 500 ml of antibodies for injection treatment.
After the yolk antibody injection is carried out in the native chicken, it is necessary to control the enteritis, E. coli and other diseases of the native chicken, and prevent the mixed occurrence of infectious bursitis and other diseases in the chicken. Therefore, in the native chicken flock, some antibiotics and antiviral Chinese medicines can be fed to improve the immunity of the native chickens.
Although there are drugs that can be controlled by infectious bursitis in turkeys, if the disease occurs, it will bring great losses to the economic benefits of farmers, so farmers must do a good job of prevention in advance when breeding native chickens, do a good job of sanitary disinfection, formulate reasonable immunization procedures for bursal vaccines, purchase healthy chicken seedlings, and select sensitive drugs for treatment. Only in this way can we prevent the occurrence of infectious bursitis in turkeys and obtain higher benefits from raising chickens!