Artificial neural networks and multiple linear regression as potential methods for modelling body surface temperature of pig

Abstract

An experiment was conducted to evaluate modelling relationships between pig's body surface temperature and ambient environment including inside and outside of pig barn. For this purpose, four different artificial neural network (ANN), including Feed Forward Back-propagation (FFB), Layer recurrent (LR), Elman (EL) and Cascade Forward Back-propagation (CFB) with different learning algorithms, transfer functions, hidden layers and neuron in each layer, and multi-linear regression (MLR) models have been performed to predict body temperature of pig. Six two-month-old pigs were studied over a period of 92 days during two years (2017-2018) to develop and evaluate the ANN and MLR models. The performance of the models in predicting pig's body temperature was determined using statistical quality parameters, including coefficient of determination (R-2), root mean square error (RMSE) and mean absolute percentage error (MAPE). The FFB model with the Levenberg-Marquardt training function, Gradient descent weight and bias learning function, Log-sigmoid transfer function and two hidden layers with 20 neurons was found as the best model. Sensitivity analysis indicated that the temperature-humidity index (THI) inside the room is the most influential factor in predicting pig's body temperature in the MLR/ANN models.