Effects of light, sound, vibration, and odour stimuli on incubation performance and chick quality in broilers and layers: a systematic review and meta-analysis

SUMMARYArtificial incubation is a critical stage in poultry production, and recent studies have explored the effects of non-conventional environmental stimuli such as light, sound, vibration, and odour on embryonic development and chick quality. This systematic review and meta-analysis aimed to evaluate the effects of these stimuli on incubation performance and chick quality in broiler and layers. Using the PICO framework, literature searches were conducted in Scopus, Web of Science, and PubMed, following PRISMA guidelines. A total of 48 studies were included: 42 on light, five on sound, one on vibration, and none on odour. All statistical analyses were performed using JAMOVI 2.5.6. In broilers, intermittent light exposure (12 h light:12 h dark) and warm-coloured light improved hatchability and chick quality (p < 0.05). In layers, only cold-coloured light affected hatchability (p < 0.05). Sound stimuli reduced incubation time in broilers (p < 0.05) but did not affect hatchability (p > 0.05). The single study on vibration was insufficient for statistical evaluation, and no studies addressing odour were identified. Overall, the findings indicate that appropriately applied light and sound stimuli may improve incubation outcomes, although the available evidence remains limited and heterogeneous. Further research is needed to standardise environmental stimuli protocols, evaluate their application on a larger scale, and determine their economic feasibility for the poultry industry.