Effects of age and diet on broiler odor during a sustainable feed trial

Odor nuisance from industrial broiler farms is driven by complex mixtures of volatile organic compounds (VOCs), yet little is known about the longitudinal development of the VOC profile during the production cycle and how diet influences those odor profiles. This pilot study provided an initial characterization of the VOC profile of feces and litter from broiler chickens at three time points in the production cycle, for dietary interventions mimicking a transition to more sustainable low-opportunity cost feed (LCF) ingredients. Three diets were applied: a control (C), low starch (LS) and low protein and starch (LSP) diet. Non-target screening (NTS) using thermal desorption-gas chromatography-mass spectrometry (TD‑GC‑MS) was used to characterize the VOC profile, and 101 VOCs were putatively identified. Although biological variation between samples was high, VOC composition of litter and feces was still found to shift significantly over time. Various ubiquitous poultry-related odorants were found to drive this shift over time in all diets. Therefore, this work provides a first resource towards more effective, time‑specific odor mitigation strategies. On the final sampling day, 8 oxygenated VOCs, including several known livestock odorants, were found to be significantly different between diets. The LS diet showed decreased abundance for 6 out of 8 odorants, suggesting that a transition to sustainable feed materials has the potential to also positively influence odor emissions when diets are balanced for essential nutrients and amino acids.