Yi Hojae, Fabian-Wheeler Eileen, Hile Michael Lee, Nguyen Angela, Cimbala John Michael
Agricultural and Biological Engineering Department, The Pennsylvania State University, University Park, PA 16802, USA.
Mechanical Engineering Department, The Pennsylvania State University, University Park, PA 16802, USA.
Animals (Basel). 2025 Aug 1;15(15):2263. doi: 10.3390/ani15152263.
Outdoor access, often referred to as pop holes, is widely used to improve the production and welfare of hens. Such cage-free environments present an opportunity for precision flock management via best environmental control practices. However, outdoor access disrupts the integrity of the indoor environment, including properly planned ventilation. Moreover, complaints exist that hens do not use the holes to access the outdoor environment due to the strong incoming airflow through the outdoor access, as they behave as uncontrolled air inlets in a negative pressure ventilation system. As the egg industry transitions to cage-free systems, there is an urgent need for validated computational fluid dynamics (CFD) models to optimize ventilation strategies that balance animal welfare, environmental control, and production efficiency. We developed and validated CFD models of a cage-free hen house with outdoor access by specifying real-world conditions, including two exhaust fans, sidewall ventilation inlets, wire-meshed pens, outdoor access, and plenum inlets. The simulations of four ventilation scenarios predict the measured air flow velocity with an error of less than 50% for three of the scenarios, and the simulations predict temperature with an error of less than 6% for all scenarios. Plenum-based systems outperformed sidewall systems by up to 136.3 air changes per hour, while positive pressure ventilation effectively mitigated disruptions to outdoor access. We expect that knowledge of improved ventilation strategy will help the egg industry improve the welfare of hens cost-effectively.
户外通道，通常称为“弹出孔”，被广泛用于提高母鸡的产量和福利。这种无笼环境为通过最佳环境控制措施进行精准鸡群管理提供了机会。然而，户外通道会破坏室内环境的完整性，包括原本规划合理的通风。此外，存在一些抱怨称，由于通过户外通道的强劲气流进入，母鸡不使用这些孔进入户外环境，因为在负压通风系统中，它们就像不受控制的进气口。随着蛋鸡行业向无笼系统转型，迫切需要经过验证的计算流体动力学（CFD）模型来优化通风策略，以平衡动物福利、环境控制和生产效率。我们通过指定实际条件，包括两个排风扇、侧壁通风口、金属丝网围栏、户外通道和静压箱进气口，开发并验证了一个带有户外通道的无笼鸡舍的CFD模型。四种通风场景的模拟结果显示，其中三种场景预测的气流速度与实测值的误差小于50%，所有场景预测的温度误差均小于6%。基于静压箱的系统每小时换气次数比侧壁系统高出多达136.3次，而正压通风有效地减轻了对户外通道的干扰。我们预计改进通风策略的相关知识将有助于蛋鸡行业以经济有效的方式提高母鸡的福利。
