Deep learning method for rapidly estimating pig body size

Abstract

Context During pig breeding, a change in a pig’s body size is an important indicator that reflects its health. However, it is difficult to extract the necessary features from images to estimate pig body size without contact. Aims It is crucial to develop a fast and accurate body size estimation algorithm to meet the practical needs of farms, i.e., numerous body size detections. Methods This report presents a rapid pig body size estimation technique based on deep learning. The YOLOv5 model is enhanced by integrating MobilenetV3, and a lightweight object detection network is introduced as the feature extraction network. An attention mechanism is also added to this system. Following these improvements, the proposed YOLOv5_Mobilenet_SE model is more suitable for the small-target detection of key parts of live pigs. A depth camera was used at a fixed height to capture the pig’s back information, which enables calculations of the critical height, i.e., the body height, of live pigs. Other key measuring points on the pig are generated according to the detection frame of the key parts located by the model. A gradient boosting regression algorithm is used to establish the body size prediction model based on the Euclidean distance between the key measuring points and the actual body size data. Key results The upgraded YOLOv5_Mobilenet_SE model achieves a mean average precision of 3.9%, which is higher than that obtained using the original YOLOv5 model. The model size is reduced from 91.2 to 10.2 M, and the average detection time for each image is 4.4 ms. The mean absolute percent errors in terms of body size, body width, and body height are 2.02%, 1.95%, and 1.84%, respectively, relative to manual measurements. Conclusions This method greatly reduces the model size and detection time while ensuring accuracy, and therefore, this method can cut costs for farms performing pig body size measurements. Implications The results of this study can provide technical support for automated and digital monitoring in the pig breeding industry.