The fungi that mainly cause aspergillosis in chickens are Aspergillus fumigatus and Aspergillus flavus. Feeding poor-quality or moldy feed, such as moldy corn, bran, fish meal, or mixed feed, or using contaminated, moldy litter, is a direct cause of outbreaks. High stocking density, poor ventilation in the chicken house, large temperature differences between the inside and outside of the house, and temperature and humidity favorable to mold growth can easily trigger the disease. Summer and autumn are rainy and humid, making feed and raw materials prone to mold and spoilage. When these feeds and raw materials are used in winter, they can easily lead to aspergillosis in chickens.
1. Strengthen disinfection of hatching machines for hatching eggs. Aspergillus in the hatching machine can penetrate eggshells during incubation and infect chicken embryos, so chicks can contract aspergillosis soon after hatching. This is also a major reason why chicks aged 4 days are most susceptible to aspergillosis.
Therefore, hatching eggs must be fumigated and disinfected several times from setting until just before hatching to interrupt and control Aspergillus infection. Before setting, disinfect the hatching eggs once by fumigation with formalin; disinfect them once more at transfer and when approximately 50% of the chicks have hatched, to eliminate Aspergillus thoroughly. Method: Based on the volume of the chicken house, calculate the total amount of formalin required using a rate of 30-40 milliliters/cubic meter, then mix it with water at a ratio of 1∶1. Pour the mixture into a metal container. Use one honeycomb briquette stove for every 50-100 cubic meters of space, placing it near a window and lighting it. Put the container holding the formalin solution on the stove to heat. The operator should observe through the window. When the liquid has evaporated, cover the head securely with a transparent plastic bag, enter the house, move the metal container away, close the entrance, and keep the house sealed for more than 24 hours.
2. Do not feed moldy or spoiled feed. Avoiding moldy litter and feed is a key measure for preventing aspergillosis. During the hot, humid summer and autumn, reduce the amount of feed purchased each time so that it is used up in about 1 weeks, keeping it fresh. Feed in small amounts several times a day. In particular, when using wet-mixed mash, feed smaller amounts more frequently and distribute the feed evenly several times.
3. Maintain cleanliness in the chicken house. Clean the drinking troughs or drinkers at least 1-2 times a day to prevent mold growth. Fit the chicken house with screens to keep flies out. The house should therefore be kept clean, hygienic, and dry, not damp. Disinfect weekly with a disinfectant containing sodium dichloroisocyanurate that can kill molds and fungi, and also disinfect the drinking water. If the litter becomes moldy, replace it promptly; alternatively, disinfect the flock with 0.5% peracetic acid.
4. Improve ventilation and air exchange inside the house. In summer, when temperatures are high, increase ventilation in the chicken house to remove hot, stale air and harmful gases such as ammonia and hydrogen sulfide. This also effectively lowers the temperature and humidity inside the house and reduces the amount of mold in the air. Most airborne mold infects the flock through the respiratory tract; less mold means fewer opportunities for infection. When it is very hot, natural ventilation may provide insufficient airflow, so exhaust fans can be switched on as needed to increase exhaust airflow. However, broiler chicks need to be kept warm during the brooding period, and temperature differences should not be too large. Gradually lower the house temperature and increase exhaust ventilation as the chicks age, balancing heat retention and ventilation.