THE STRESS OF NOT BEING ABLE TO PERFORM DUSTBATHING IN LAYING HENS

The stress of not being able to perform dustbathing was studied in sma ll groups of laying hens. The birds were reared and kept for 2.5 years in cages with either sand (''sand birds'') or wire floors (''wire bir ds''), and subsequently deprived of sand (sand birds) or given access to sand (wire birds). Before this change, wire birds had a higher inci dence of unilateral wing/leg stretching and stereotypic pecking compar ed to sand birds; however, there was no difference in corticosterone c oncentrations. Deprivation of sand in the sand birds resulted in a tot al absence of dustbathing and in a significant increase in corticoster one concentrations. Although the wire birds dustbathed on the wire bef ore the change of floors, there was a significant increase in the inci dence of dustbathing after sand was provided, but no changes in the co ncentrations of corticosterone. Threats and allopecks decreased in the wire birds after access to sand, whereas no changes were found in the sand birds. Stereotypic pecks on feathers were absent in the sand bir ds, but were frequent in most of the wire birds both before and after they were given sand. Also, in the wire birds, all feather pecking (st ereotypic and nonstereotypic) was positively correlated with the conce ntration of corticosterone, and this kind of pecking may, thus, be an expression of stress in laying hens. We conclude that the nonperforman ce of dustbathing behavior is associated with the experience of stress . (C) 1997 Elsevier Science Inc.