A multifactorial way to assess litter stability and ammonia risk in broiler production: effects across age (7–39 days) and thermal environments

Ammonia (NH3) emissions from broiler litter pose a significant challenge in poultry production, impacting bird welfare, respiratory health, and overall performance. These emissions are governed by dynamic interactions among environmental and litter variables such as temperature, moisture, and pH, which are often studied in isolation. This study proposes a multifactorial index to assess the stability of poultry litter and its influence on ammonia (NH3) volatilisation under different thermal environments. Broiler houses were subjected to Comfort, Cold, and Hot conditions at different stages of the birds’ growth, and variables such as litter temperature, pH, moisture, and NH3 were measured. A Combined Stress Index (CSI) was developed by standardising and integrating litter temperature, moisture, and pH. The results revealed that heat stress significantly increased litter degradation, moisture retention, and NH3 levels, particularly in the final stages of production. The CSI showed a strong correlation with NH3 concentration (r = 0.82), suggesting its potential as a predictive tool. This index offers a practical framework for real-time monitoring and early intervention in precision livestock farming systems, especially in climates where environmental instability accelerates litter deterioration.