Use of vocalisation to identify sex, age, and distress in pig production

To assess animal welfare at a pig production farm is a time-consuming task. The present study aimed to investigate the differences in pig vocalisation as a function of the sex, age, and distress conditions, and to propose a way of identifying distressful situations. The individual vocalisations of 40 pigs were recorded (20 male and 20 female) during exposure to different distress in the farrowing, nursery, growth, and finishing phases. Vocalisation pitch differed between males (194.5 Hz) and females (218.2 Hz). Pig vocalisation was also different according to age, especially for the attributes of maximum and minimum amplitudes, and the frequency of formant 2. Diverse distress situations also were identified by various acoustic attributes. A decision-tree for classifying the distress condition for pigs was built (with an accuracy of 81.92%) using the machine-learning technique. Results indicate the possibility of estimating pig welfare by recording the vocalisation. The algorithm is also promising to identify pig sex and age.