Detailed Explanation of Prevention and Treatment Methods for Chicken Oviduct Cysts

Content: In recent years, a disease characterized by low egg production rate and poor development or fluid accumulation in the oviduct has appeared in laying hen flocks. This disease mostly occurs between 150-200 days of age, and once it occurs, there is no cure, only culling, resulting in huge losses. Through epidemiological research and experimental testing, it is believed that this disease is caused by infectious bronchitis virus.

I. Epidemiology

This disease can occur in chicken flocks of all breeds. Before 2000, it was mostly found in parent breeder flocks. In recent years, the incidence rate in commercial flocks has increased significantly. After the flock begins laying, diseased chickens with oviduct fluid accumulation gradually appear. The higher the proportion of diseased chickens, the lower the egg production rate. Generally, the peak egg production rate ranges from 30%-80%. In some flocks, after culling the diseased chickens, the egg production rate can reach 90%.

Affected flocks are mostly those raised during the cold season (generally from January to March). Farms that brood multiple consecutive batches are prone to this disease. This disease does not undergo vertical transmission, meaning that among flocks from the same breeder farm, some may be affected while others are not. Extensive clinical investigations show that flocks are infected during the brooding period, but most do not show severe clinical symptoms. The symptoms during the laying period are manifestations of IB sequelae.

II. Clinical Symptoms and Pathological Changes

The flock appears completely normal in external appearance, but egg production has no peak, generally ranging from 30%-80%. Diseased chickens have thick, bright red combs (sometimes appearing redder than those of normal chickens) and drooping abdomens. Necropsy reveals blisters of varying sizes in the oviduct, with the largest containing over 600 ml and the smallest containing a few ml. The accumulated fluid is clear, colorless, transparent, and odorless. Some chickens have no fluid accumulation in the oviduct but have a blind end, oviduct stenosis, or no oviduct opening. Most diseased chickens have normal follicle development. Some chickens have 6-7 mature eggs in the abdominal cavity but no fully functional oviduct, making egg laying impossible. Other organs show no abnormalities.

III. Treatment and Prevention

Through extensive clinical trials, it has been shown that this disease is not caused by Chlamydia but by infectious bronchitis virus. That is, when flocks are infected with infectious bronchitis virus in the early stage, it causes lifelong damage to the oviduct, affecting egg production. There is no effective treatment for this disease; only culling of diseased chickens is possible. If the flock's egg production rate is too low, the entire flock should be culled.

IV. The following methods can be used for prevention

1. Ensure relatively stable brooding temperature during the brooding period. The temperature difference within 24 hours must not exceed 3°C-5°C.

2. The temperature during early brooding should be as high as possible, generally reaching 35°C-38°C at 1-3 days (as long as the chickens are evenly distributed, a slightly higher temperature is better). Then reduce by 2°C-3°C every 3 days.

3. Contaminated brooding houses must be strictly disinfected and left empty for at least 1 month before introducing chicks for brooding.

4. At 1-3 days of age, immunize with infectious bronchitis freeze-dried vaccine by nasal drip and eye drop.