When autumn and winter arrive, especially in 11-12 when the weather swings between cold and warm, Newcastle disease can easily “come knocking.” Once a flock is infected, symptoms may range from lethargy, loss of appetite and difficulty breathing to, in severe cases, twisted necks and circling. The disease progresses quickly and can cause many deaths, making it a major concern for poultry farmers.
In response, the Smart Layer Hot Topics column, featuring expert insights, has put together the key measures for autumn and winter prevention and control from two perspectives—how to recognize the disease and how to prevent it—to help flocks get through the winter safely.
一、了解新城疫的“小脾气”，早知道早提防
This disease can occur throughout the year, but it is most active from 10 through 3 of the following year. It is especially prevalent during seasonal transitions and sudden weather changes. Chickens of any age can be infected, with pre-lay flocks and birds at peak production being most susceptible.
If the flock has been vaccinated and has not contracted another bacterial disease, there may be fewer deaths. However, replacement pullets may have “sequelae” after recovering, such as twisted necks or circling. The situation is more troublesome for laying hens: at first, they may show only mild respiratory symptoms, but after 4-5 days, the egg production rate may “plummet,” falling to around 15% before gradually recovering. It may never return to its previous high level, and many soft-shelled, small, and misshapen eggs may also be laid. In addition, the disease spreads very quickly: if one chicken is infected, it can spread throughout the flock within 2 days. Fortunately, the virus types are stable, and as long as chickens have antibodies in both their mucous membranes and body fluids, they can be effectively protected.
二、抓住四大防控关键，守住鸡群健康
1、Immunization is key: “dress” the flock in protective gear
Immunity cannot rely on just one type of vaccine. Live and inactivated vaccines need to be used together to be effective: live vaccines can induce mucosal antibodies in chickens, especially protecting the respiratory mucosa, and are suitable for primary immunization; inactivated vaccines can induce higher levels of humoral antibodies in chickens and work better as a supplement. Suggested timing is as follows:
Brooding and rearing period: Give 3 live-vaccine immunizations. On farms that cannot test maternal antibody levels, use a safe, low-virulence vaccine such as Clone30 or the VH strain for the first immunization within 1 weeks; use the La Sota strain for a second booster at 3-4 weeks; and give the third immunization at 60-70 days of age.
Around the start of laying: Give another booster before the hens are about to lay eggs (110-120 days of age) to ensure a smooth start to laying; after laying begins, give a live-vaccine booster every 2-3 months.
In addition, when using live vaccines, it is best to pair them with oil-emulsion vaccines. It is recommended to give injections at 60 and 120 days of age; in high-incidence areas, during the brooding period at 1-2 weeks, inject 0.25mL of oil-emulsion vaccine at the same time as the live vaccine. During the laying period, if the mean antibody level monitored is below 8log2, give a booster promptly.
2, the environment is fundamental: reduce places where viruses can “hide”
On the one hand, control the movement of people and items: outsiders should not enter the chicken houses freely, and staff must shower before entering; personal belongings must not be brought into the production area. Production equipment and supplies such as immunization equipment, egg carts, and egg crates should be dedicated to one chicken house and never shared between houses, to prevent viruses from spreading through these “vehicles.”
On the other hand, ensure thorough disinfection: routine cleaning and disinfection inside and outside the chicken houses are essential, and should be intensified at particular times:
When the flock is in an antibody gap period, is at a susceptible stage, and has respiratory symptoms, use a disinfectant that can kill viruses and disinfect several times.
For 3 days before and after administering a live attenuated vaccine, do not use disinfectants that kill viruses, and do not disinfect around the immunized poultry house. Once the chickens begin shedding the virus, disinfect thoroughly to prevent the vaccine virus from spreading;
After strong winds and heavy rain, first clean up the external environment, then disinfect thoroughly to eliminate pathogens brought to the surface by rainwater.
3, monitoring is key: detect problems early and “limit the losses”
As part of routine care, follow the “four checks”:
First, check the flock: observe the chickens’ general condition and respiratory symptoms. These are the earliest signs of illness. If chickens appear lethargic or have abnormal breathing sounds, promptly watch for other symptoms;
Second, perform necropsies: for flocks at susceptible ages, during epidemic seasons, or in suboptimal health, perform necropsies on dead chickens to check for the characteristic lesions mentioned earlier;
Third, check antibody levels: for these same special flocks, test antibody levels every half month. If there are abnormalities, test weekly to track antibody trends and adjust the timing of immunization promptly;
Fourth, monitor the egg production rate: once it is confirmed that a drop in the egg production rate is caused by Newcastle disease, this means the virus has already spread, and immediate action is needed.
After detecting an abnormality, take these four steps without delay: ① Isolate and disinfect: separate sick chickens from susceptible chickens, and disinfect the external environment continuously for 24 hours; ② Emergency immunization: administer aerosol immunization to sick chickens, nearby flocks, and susceptible flocks using a live attenuated La Sota strain vaccine at 4 times the dose; ③ Track and monitor: assign a dedicated person to perform necropsies. This person must not enter the production area or come into contact with the chickens. Also monitor the recovery of both healthy and sick chickens; ④ Provide nutritional supplements: give the chickens some multivitamins and, if necessary, antibiotics to prevent secondary bacterial diseases and reduce deaths.
4, physical condition is the key: keep the flock “strong and healthy”
A healthy flock has stronger disease resistance. Make sure there is enough drinking water and feed every day, and provide a balanced diet. Do not feed moldy or spoiled feed;
Ensure proper ventilation in the chicken house. Uneven ventilation can cause respiratory diseases, which may in turn trigger Newcastle disease;
Also try to minimize stress. For example, during weather changes, flock transfers, or immunization, if stress is frequent and unavoidable, give the chickens anti-stress medication and provide a stable, comfortable environment so the flock can better resist disease.
In short, the key to preventing Newcastle disease during the autumn-to-winter seasonal transition lies in these four areas: “immunization, environment, monitoring, and physical condition.” If vaccination is carried out properly, the environment is well controlled, abnormalities are detected early, and the flock is kept strong and healthy, losses can be minimized and the flock can safely get through the seasonal transition!