The scent of safety? Behavioural responses of turkeys to varying ammonia concentrations

Abstract

Ammonia is a common airborne contaminant in poultry housing, originating from the microbial breakdown of bird excreta, and is known to adversely affect bird health and behaviour. Despite the use of ventilation and management practices to control its levels, concentrations frequently exceed recommended thresholds. While the effects of ammonia are well-documented in broilers and laying hens, empirical data on turkeys remain limited. Turkeys experience prolonged exposure due to longer rearing periods and may exhibit different behavioural sensitivities. This study investigated short-term behavioural effects of ammonia at 0 (fresh air), 25, and 45 ppm from both natural (excreta-derived) and artificial (cylinder) sources on Hybrid XL turkeys. Twenty female turkeys were repeatedly tested in a two-chamber apparatus and video recorded. Behavioural data including latencies to enter (LTE) and forage (LTF), foraging, avoidance, and vocalisations were analysed. Survival analysis accounted for censored latency data, modelling individual and session effects as random intercepts. Cox mixed-effects models were used to estimate hazard ratios (HR). Latency to forage and enter were significantly reduced at 25 ppm natural ammonia compared to fresh air (HR_LTF = 1.89; HR_LTE = 2.16), indicating faster engagement. Latency to forage was also reduced at 45 ppm natural ammonia (HR = 1.74). No significant differences were observed between ammonia sources in latency or behaviours. Foraging frequency and duration were unaffected. Aversive behaviours showed no significant treatment effects, though vocalisation frequency decreased by 45.3% at 45 ppm artificial ammonia compared to fresh air. Results suggest turkeys may exhibit limited overt behavioural aversion to ammonia at tested concentrations. Behavioural indicators alone may underestimate welfare impacts. Future research should integrate behavioural, physiological, and health metrics over longer periods to inform air quality standards tailored to turkeys.