- 1Animal Welfare Research Group,
Department of Production Animal Clinical Science, Faculty of Veterinary
Medicine and Biosciences, Norwegian University of Life Sciences (NMBU),
Oslo, Norway
- 2Emotion and Cognition Group, Department of Farm Animal Health, Utrecht University, Utrecht, Netherlands
Spatial cognition in vertebrates is adversely affected by a lack
of environmental complexity during early life. However, to our
knowledge, no previous studies have tested the effect of early exposure
to varying degrees of environmental complexity on specific components of
spatial cognition in chickens. There are two main rearing systems for
laying hens in the EU: aviaries and cages. These two systems differ from
one another in environmental complexity. The aim of the present study
was to test the hypothesis that rearing in a barren cage environment
relative to a complex aviary environment causes long-lasting deficits in
the ability to perform spatial tasks. For this purpose, 24 white Dekalb
laying hens, half of which had been reared in an aviary system and the
other half in a conventional cage system, were tested in a holeboard
task. Birds from both treatment groups learnt the task; however, the
cage-reared hens required more time to locate rewards and had poorer
levels of working memory. The latter finding supports the hypothesis
that rearing in a barren environment causes long-term impairment of
short-term memory in chickens.
Fernanda M. Tahamtani
Janicke Nordgreen
Rebecca E. Nordquist
Andrew M. Janczak