Levels of two pollutant gases, temperature, and relative humidity and their influence on broiler welfare

Air quality is important for animal welfare, especially for barn-housed broilers. Modern sensors can measure concentrations of pollutant gases such as ammonia (NH 3 ) and carbon dioxide (CO 2 ) in short intervals but are not routinely used on broiler farms. This study investigated how fluctuations in climate parameters during individual fattening periods affect broiler welfare under practical conditions. We equipped 2 farms with sensors and recorded NH 3 and CO 2 concentrations, temperature, and relative humidity. To examine relationships between these climate parameters and animal welfare indicators, we assessed body weight, foot pad dermatitis, hock burn, plumage soiling, lesions in the cloacal region, and gait score of the broilers at the end of a fattening period. The results showed that NH 3 concentrations stayed low at the beginning of a fattening period and increased towards slaughter age, whereas CO 2 accumulated at the beginning. Fattening periods with elevated NH 3 concentrations showed altered risks for the occurrence of foot pad dermatitis and hock burn, whereas periods with elevated CO 2 concentrations tended to show altered risks of plumage soiling, foot pad dermatitis, and body weight changes. The study demonstrates that the dynamic of the 2 pollutant gases is complex. They do not have a temporal relationship in their concentration profiles, and therefore, both gases need to be monitored. Continuous monitoring offers valuable insights for improving housing conditions, such as adjusting ventilation strategies. Although a tested automated ventilation adjustment did not reduce gas concentrations, the findings underline the importance of sensor-guided climate control and farm-specific solutions to promote both animal welfare and high air quality standards.