Long-Term Measurement of Piglet Activity Using Passive Infrared Detectors

SIMPLE SUMMARY: The activity of weaned piglets on a commercial farm was measured using passive infrared detectors during six breeding cycles. Highly heterogeneous daily behaviors were observed. A high level of movement was detected immediately after weaning, followed by a sudden drop and a subsequent stabilization throughout the cycle. The real series were best characterized by models with a single peak of activity. ABSTRACT: Measuring animal activity is useful for monitoring animal welfare in real time. In this regard, passive infrared detectors have been used in recent years to quantify piglet activity because of their robustness and ease of use. This study was conducted on a commercial farm in Northwest Spain during six complete breeding cycles. The hourly average activity of weaned piglets with a body mass of 6–20 kg was recorded and further analyzed by using a multiplicative decomposition of the series followed by a wavelet analysis. Finally, the real series were compared to the theoretical models of activity. Results showed a high level of movement immediately after weaning and a sustained level of activity throughout the cycles. The daily behavior of the piglets followed a clear circadian pattern with several peaks of activity. No differences in behavior were observed between spring–summer cycles and autumn–winter cycles. Single-peak models achieved the best predictive results. In addition, the installed sensors were found to underestimate mild activity.