Ventilation refers to the process of removing harmful gases from the house into fresh air. Persistent and high concentrations of harmful gases can cause anemia, weaken the system, reduce production performance and disease resistance, and are particularly susceptible to respiratory disease and ascites disease, causing significant losses to broiler production. Ventilation requirements have a certain relationship with the human senses, through the human senses to express whether the chicken can adapt to the air of the chicken house, as shown in Table 1.

Table 1 Ammonia gas concentration and human sensory indicators