Winter is a peak season for respiratory diseases in laying hens. Once a respiratory disease breaks out in a flock, it can cause reduced feed intake, lower egg production, and decreased egg quality in mild cases, while severe cases may lead to mixed infections and serious economic losses. Therefore, understanding why respiratory diseases are prevalent in laying hens during winter and taking effective prevention and control measures can help ensure the flock overwinters safely.
一、Reasons for the high incidence of respiratory diseases in laying hens during winter
1, Inadequate environmental management
The conflict between heat retention and ventilation: In winter, laying hen farmers often reduce ventilation to maintain the temperature in the poultry house. This causes concentrations of harmful substances such as ammonia, hydrogen sulfide, and dust to rise sharply inside the house. Excessively high ammonia concentrations can irritate and damage the integrity of the chickens’ respiratory mucosa, thereby opening the door wide to viral and bacterial invasion.
Humidity imbalance: Poultry houses commonly have low humidity in winter. Dry air can cause the chickens’ respiratory mucosa to become dry and cracked, weakening ciliary movement and reducing its ability to clear foreign matter. It also reduces the respiratory tract’s ability to resist pathogens.
Temperature stress and drafts: Large day-to-night temperature differences, or “drafts” caused by poorly sealed doors and windows in the poultry house, can expose the flock to severe cold stress. This stress can weaken the chickens’ immunity and become an important trigger for disease.
2, Active pathogenic microorganisms
On the one hand, Escherichia coli, Mycoplasma and other pathogens are widespread in the environment. When poor environmental conditions weaken a flock’s resistance, these pathogens can multiply rapidly and cause diseases such as chronic respiratory disease in chickens (mycoplasmosis) and colibacillary airsacculitis. On the other hand, winter is the peak season for viral diseases such as avian influenza (AIV), Newcastle disease (ND) and infectious bronchitis (IB). These viruses can cause severe respiratory symptoms on their own and often lead to secondary bacterial infections, making the disease more severe and increasing mortality.
3, flock-related factors
On the one hand, during the laying period, hens are under considerable physiological stress. Their reproductive systems are under heavy strain, and they are highly sensitive to nutritional and environmental changes, with relatively weak immune defenses. On the other hand, if a flock has latent immunosuppressive diseases such as infectious bursal disease (IBD) or Marek’s disease (MD), these can seriously weaken vaccine effectiveness and the birds’ overall disease resistance, making respiratory diseases more likely to occur and spread.
二、Prevention and control of respiratory diseases in laying hens in winter
To meet the challenge of respiratory diseases in winter, the principle of “prevention first, prevention and treatment combined” must be followed.
1, pay attention to environmental control
To address common winter environmental problems, poultry farm managers should abandon the reluctance to ventilate and increase ventilation when temperatures are higher at midday. At the same time, ensure that poultry houses are well sealed to prevent drafts. In addition, clean up manure regularly and reduce feed dust.
2, scientific feeding and management
Balanced nutrition: Provide high-quality feed to ensure an adequate supply of vitamins (especially vitamins A, C, and E), trace elements, and amino acids to enhance the mucosal system’s repair capacity and the body’s ability to resist stress.