Periodicity Intensity of the 24 h Circadian Rhythm in Newborn Calves Show Indicators of Herd Welfare

TL;DR

This study uses accelerometer data from newborn calves over 8 weeks to analyze 24-hour circadian rhythm intensity, revealing herd welfare indicators through movement pattern analysis.

Contribution

It introduces a method to quantify circadian rhythm strength from movement data as a welfare indicator in livestock.

Findings

Circadian rhythm intensities increase and decrease synchronously among calves.

Movement data processing reveals external welfare factors affecting the herd.

The method provides insights beyond simple movement analysis.

Abstract

Circadian rhythms are a process of the sleep-wake cycle that regulates the physical, mental and behavioural changes in all living beings with a period of roughly 24 h. Wearable accelerometers are typically used in livestock applications to record animal movement from which we can estimate the activity type. Here, we use the overall movement recorded by accelerometers worn on the necks of newborn calves for a period of 8 weeks. From the movement data, we calculate 24 h periodicity intensities corresponding to circadian rhythms, from a 7-day window that slides through up to 8-weeks of data logging. The strength or intensity of the 24 h periodicity is computed at intervals as the calves become older, which is an indicator of individual calf welfare. We observe that the intensities of these 24 h periodicities for individual calves, derived from movement data, increase and decrease synchronously in a herd of 19 calves. Our results show that external factors affecting the welfare of the herd can be observed by processing and visualising movement data in this way and our method reveals insights that are not observable from movement data alone.