Illuminating Solutions for Reducing Mislaid Eggs of Cage-Free Layers

Social dynamics and lighting conditions influence floor egg-laying behavior (FELB) in hens. Hens prefer to lay eggs in darker areas, leading to mislaid eggs in cage-free systems. Consistent lighting is crucial to prevent mislaid eggs, but equipment obstructions can result in a dark floor area. These dark areas entice hens to lay their eggs outside the designated nesting area, which can lead to potential losses, damage, or contamination, creating hygiene problems and increasing the risk of bacterial growth, resulting in foodborne illnesses. Therefore, additional lighting in dark areas can be a potential solution. The objectives of this study were to evaluate the effectiveness of providing additional light in darker areas in reducing the number of mislaid eggs and FELB. Approximately 720 Hy-Line W-36 hens were housed in four cage-free experimental rooms (180 hens per room), and 6 focal hens from each room were randomly selected and provided with numbered harnesses (1–6) to identify which hens were performing FELB and identify the effect of illuminating solutions. Eggs laid on the floor and in nests were collected and recorded daily for two weeks before and after the light treatment. Statistical analysis was performed using paired t-tests for mislaid eggs and logistic regression for FELB in R Studio (p < 0.05). This study found that additional lighting in darker areas reduced the number of mislaid eggs by 23.8%. Similarly, the number of focal hens performing FELB decreased by 33.3%. This research also unveiled a noteworthy disparity in FELB, with approximately one-third of hens preferring designated nesting areas, while others opted for the floor, which was influenced by social dynamics. Additionally, egg-laying times varied significantly, ranging from 21.3 to 108.03 min, indicating that environmental factors and disturbances played a substantial role in this behavior. These findings suggest that introducing additional lighting in darker areas changes FELB in hens, reducing mislaid eggs and improving egg quality in cage-free systems.