Analytical and Numerical Modeling of Skin Surface Temperature in Livestock

Heat exchange between livestock and environment is very complex. It is influenced by environmental factors (air temperature, relative humidity, wind speed and solar radiation) and animal factors such as metabolic heat generation, sweating, heat dissipation by convection, radiation and respiration. The heat exchange models between livestock and environment available in the literature are simplified models that do not consider all these aspects. We developed a comprehensive analytical model that predicts heat exchange between a pig and the environment. Physiological parameters (skin temperature, rectal temperature) and environmental parameters (air temperature, black globe temperature and wind speed) were measured to validate the model. The model is one-dimensional and was developed based on the principles of energy balance. The predicted skin surface temperatures were compared against measured values using the correlation-regression and deviation approaches. The measured mean core temperature and skin surface temperature were 39.33±0.047 °C and 35.43±0.089 °C, respectively. The predicted skin temperatures by the analytical approach was 35.38 ±0.11°C and by the numerical approach was 35.68±0.10°C suggesting that there was no statistical difference (P>0.05) between the predicted and measured values. In addition, a strong correlations (r = 0.866 for the analytical and 0.865 for the numerical) between the measured and the predicted skin surface temperatures were obtained.