In early winter, temperatures drop sharply and the day-night temperature difference widens, bringing laying hens into a high-risk period for respiratory diseases. These diseases threaten the health and production performance of laying hens and constrain the profitability of early-winter poultry farming. This article reviews the causes of respiratory diseases in laying hens and outlines prevention and control measures for poultry farmers’ reference.
I. Causes of Respiratory Diseases
1, Environmental Factors
(1) Ventilation
In early winter, temperatures fall quickly and the day-night temperature difference is large. To retain heat, ventilation is often reduced, causing concentrations of harmful gases such as ammonia and hydrogen sulfide in poultry houses to rise. These gases irritate the respiratory mucosa and can trigger disease.
(2) Humidity and Dust
The air becomes dry and humidity decreases, increasing airborne particles such as dust and feather fragments. Hens can easily inhale these particles into their respiratory tracts, where they attach to the mucosal surface and cause infection.
(3)Stocking density
Excessive stocking density in the chicken house can impede air circulation and increase the likelihood of pathogen transmission.
2, pathogen infection
(1)Viruses
Viruses such as avian influenza, Newcastle disease, infectious bronchitis, and infectious laryngotracheitis can directly damage respiratory epithelial cells, causing respiratory symptoms.
(2)Bacteria
Bacteria such as Escherichia coli and Salmonella can spread through contaminated feed, drinking water, air, and other sources, causing respiratory infections.
(3)Mycoplasma
Mycoplasma gallisepticum is a pathogen that causes chronic respiratory disease and can be widespread in flocks. When affected by external triggers such as stress or poor environmental conditions, it can cause respiratory disease.
3, Stress factors
(1) Immunization
Improper practices, such as selecting an unsuitable vaccine, using an inappropriate vaccination dose, or following an unreasonable immunization schedule, can trigger stress responses in the flock, damage the respiratory mucosa, and reduce resistance, thereby causing respiratory disease.
(2) Management stress
Management-related stressors such as cold stress, flock transfers, feed changes, and changes in lighting can reduce the flock’s resistance to pathogens and increase the risk of respiratory disease.
II. Prevention measures
1, Precisely regulate the poultry-house environment
(1)Manage temperature effectively
Ensure the temperature in the poultry house remains stable and within the ideal range of 13~18℃. Also minimize temperature fluctuations: changes should not exceed 1℃ per hour, and the temperature difference between day and night should remain within 3℃. Avoid sudden temperature changes that may cause stress in the flock.
(2)Strengthen ventilation management
Provide ventilation while meeting the minimum air exchange requirements. By adjusting the operating time and power of the ventilation equipment, keep the air in the poultry house fresh and circulating, and maintain the concentration of harmful gases such as ammonia below safe limits (ammonia concentration <10ppm).
Pay attention to the direction and speed of incoming air. Adjust the small-window angle to prevent cold air from blowing directly onto the flock, causing cold stress and affecting its health and production performance.
(3)Manage humidity effectively
Use methods such as scheduled misting and water spraying or installing and operating humidification equipment to maintain the humidity in the poultry house within the optimal range of 50%~60%. This helps ensure the normal physiological function of the flock’s respiratory mucosa and effectively reduces the risk of respiratory mucosal damage caused by low humidity, creating a healthy and comfortable rearing environment for the flock.
2, Strengthen biosecurity management
(1) Implement isolation measures
Fully implement the site’s disease prevention and control management system and operating procedures. Apply tiered and categorized controls to all entry and exit routes, with particular emphasis on closed-loop management of external personnel, vehicles, and supplies.
Establish a daily inspection mechanism to supervise and check the implementation of isolation measures, ensuring that all disease prevention and control requirements are fully and effectively carried out.
(2) Implement disinfection measures
Clean the poultry houses every day to create a comfortable environment for the flock. Follow scientific disinfection procedures and plans to ensure effective disinfection of 100% of the environment inside and outside the poultry houses, creating an environment free of pathogenic microorganisms for the flock. Dispose of dead chickens on the premises in a harmless manner to reduce sources of infection.
(3) Carry out immunization
Develop a scientifically sound and appropriate immunization program based on local disease conditions and the actual circumstances of the flock. Select vaccines produced by reputable manufacturers to ensure their quality and effectiveness.
Administer vaccinations strictly in accordance with the vaccine instructions, paying attention to the dosage, method, and timing. After vaccination, observe the flock’s response and promptly address any adverse reactions that may occur.
(4) Regular antibody testing
Regularly monitor antibody levels for diseases such as Newcastle disease and avian influenza to ensure effective immunization. At the same time, based on antibody test results, administer booster vaccinations promptly to effectively protect against external pathogenic microorganisms.
3, Strengthening the flock’s resistance
(1) Ensure balanced nutrition
Provide the flock with scientifically formulated complete feed. Add vitamin A, vitamin C, and the trace element selenium to the feed to enhance respiratory mucosal repair and the body’s immunity.
In daily flock management, feed formulations should also be adjusted promptly according to the nutritional needs of the flock at different growth stages, ensuring precise and timely nutrient supply.
At the same time, ensure the feed is fresh. Avoid feeding moldy feed to prevent mycotoxins from worsening respiratory tract damage.
(2) Reduce stress factors
During rearing, minimize management practices that may trigger stress in the flock, including frequent changes to feed, stocking density, and environmental conditions, to avoid cumulative stress.
Before carrying out necessary management practices (such as flock transfers and vaccination), take appropriate measures to alleviate stress. For example, add an appropriate amount of anti-stress additives, such as electrolyte multivitamins and vitamin C, to the feed 3~5 days in advance; add an appropriate electrolyte balancer to the drinking water; and appropriately extend the transition period to reduce stress responses. These comprehensive measures can help minimize the adverse effects of stress on flock health.
In summary, preventing and controlling respiratory diseases in laying hens in early winter requires comprehensive consideration of various factors, including the environment, management, and biosecurity. Only by adopting comprehensive and systematic measures can the incidence rate be effectively reduced and laying hen performance and economic benefits safeguarded.