Synchronized lying in cattle in relation to time of day

Postural synchrony, in which cattle lie down or stand up at the same time as other members of their herd, occurs both in animals housed indoors when enough resources are available and in those out at pasture, but the mechanisms by which such synchrony is achieved are poorly understood. We report a study of 6 groups of young cattle (Bos taurus) at pasture in which our aim was to study postural synchrony at different times of day and in relation to the postures of neighbouring cattle.All of the observed groups exhibited a high degree of synchrony in lying/standing, as 70% of animals in a group exhibited the same posture over 93% of the time. Time of day had a significant effect (P≈0.0046): cattle were least synchronized in the middle of the day and most synchronized in the morning and evening. With the increasing use of synchrony of lying as a measure of welfare in cattle, such temporal effects need to be taken into account.Cattle were more synchronized with the posture of a near neighbour than they were with that of a randomly chosen member of the herd (P≈0.016), suggesting that cattle were actively synchronizing their postures with that of their neighbours. These results indicate that a full understanding of the mechanisms of postural synchronization in cattle herds will need to incorporate both collective (allelomimetic) and concurrent (individual) responses.