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Exploring piling behavior in aviary-housed laying hens in response to age, management practices, and social
Valentina Bongiorno1, Ahmed B A Ali2, Janice M Siegford1
1Department of Animal Science, Michigan State University, 474 S. Shaw Lane, East Lansing, Michigan, 48824-1225, United States of America.
Abstract:
Piling behavior (PB) represents a poorly understood although relevant economic and welfare issue in laying hens housed in cage-free systems. The current study described possible social facilitation effects on PB using video recordings collected at 17, 27, and 44 weeks of age (WOA) in partial or continuous litter-access aviaries. A flock of 1152 Hy-line brown laying hens were allotted to 2 rooms each equipped with 4 units (144 birds/unit) separated by wire mesh partitions. Hens in one room had continuous litter access, while in the other room birds were kept off litter from lights on until 1200 between 17 and 32 WOA. Evaluation of PB was performed using video footage collected over 48 h at 17, 27, and 44 WOA. Descriptive statistics regarding pile characteristics (number of piles, dimension, duration, preceding events observed, birds involved/total on litter, and activity of adjacent units) were performed. A Monte Carlo analysis was applied to explore possible social facilitation. A total of 95 piling events lasting from 1.25 to 65.67 min were recorded and involved 10 to 69 birds; most of the piles involved over 50% and up to 100% of birds on litter. No piling events were observed at 17 WOA. More piling events were observed in control (CON) hens at 27 WOA than partially enclosed (PARR) birds (30vs19), suggesting that time available on litter may influence PB frequency. Furthermore, more preceding events were identified at 44 WOA than at 27 WOA, despite an overall similar number of piling events. The start of a pile in one unit generally did not relate to changes in behavior in neighboring units; furthermore, the results of the Monte Carlo simulation pointed towards the absence of social facilitation, as the clusters of piling events were not greater than what would be observable by chance. The present study provides preliminary insights into PB occurrence in relation to a floor egg management strategy across different ages.
