A dynamic model describing the thermal balance of Holstein dairy cattle was developed. The model quantified the heat flow of five main nodes at the body core, top and bottom skin, and top and bottom coat of a dairy cow. Heat production by the animal and heat flows between the animal and the environment, including conduction, convection, evaporation and radiation, were calculated based on existing models and physical principles. The model requires information of climate, animal characteristics and location as inputs, and returns body core, skin and coat temperatures as outputs. The thermal balance model was evaluated through two datasets. The root mean squared error of prediction for body temperature was 1.16 °C and 0.40 °C for the two datasets, respectively. A simulation study was conducted based on a Holstein dairy cow with 600 kg of body weight and 25 kg of daily milk yield under a typical summer environment in California, USA for three days. The average simulated temperatures of body, top and bottom skin, and top and bottom coat were 40.9, 35.6, 35.9, 34.1 and 33.7 °C, respectively. A local and a global sensitivity analyses showed that heat production, surface area and the parameters relative to respiration and sweating were the most sensitive. The model is able to predict the dynamic change of body temperature under hot weather, and to guide the use of physical cooling strategies, such as shade, fans, sprinklers and cooling mats in dairy facilities.

开发了描述荷斯坦奶牛热平衡的动态模型。该模型量化了奶牛身体核心、顶部和底部皮肤以及顶部和底部涂层的五个主要节点的热流。动物产生的热量以及动物与环境之间的热量流动，包括传导、对流、蒸发和辐射，都是根据现有模型和物理原理计算得出的。该模型需要气候、动物特征和位置信息作为输入，并返回身体核心、皮肤和皮毛温度作为输出。热平衡模型通过两个数据集进行评估。对于两个数据集，体温预测的均方根误差分别为 1.16 °C 和 0.40 °C。以一头体重 600 公斤、日产奶量为 25 公斤的荷斯坦奶牛在美国加利福尼亚州典型夏季环境下进行为期三天的模拟研究。身体、上下表皮、上下被毛的平均模拟温度分别为40.9、35.6、35.9、34.1和33.7°C。局部和全局敏感性分析表明，产热、表面积以及与呼吸和出汗相关的参数最敏感。该模型能够预测炎热天气下体温的动态变化，并指导乳制品设施中物理降温策略的使用，如遮阳、风扇、喷头和冷却垫。顶部和底部皮肤以及顶部和底部涂层的温​​度分别为 40.9、35.6、35.9、34.1 和 33.7 °C。局部和全局敏感性分析表明，产热、表面积以及与呼吸和出汗相关的参数最敏感。该模型能够预测炎热天气下体温的动态变化，并指导乳制品设施中物理降温策略的使用，例如遮阳、风扇、喷头和冷却垫。顶部和底部皮肤以及顶部和底部涂层的温​​度分别为 40.9、35.6、35.9、34.1 和 33.7 °C。局部和全局敏感性分析表明，产热、表面积以及与呼吸和出汗相关的参数最敏感。该模型能够预测炎热天气下体温的动态变化，并指导乳制品设施中物理降温策略的使用，如遮阳、风扇、喷头和冷却垫。