Using motivation to feed as a way to assess the importance of space for broiler chickens

This paper describes a novel combination of feeding motivation and spatial preference testing. We used the feeding motivation test to determine a `low' barrier height that broiler chickens, Gallus gallus domesticus, that were not food deprived would cross to get to food, and a `high' barrier height that food-deprived chickens would cross to get to food. These barriers were then used to assess the chickens' spatial preferences. Birds could show their spatial preference by moving between two compartments with different stocking densities (14.7 birds/m(2) in a compartment of fixed size versus 9.3, 12.1 or 14.7 birds/m(2) in a compartment of adjustable size). The compartments were separated by either the low or the high barrier. In the density preference test, the number of birds in the adjustable compartment increased with increasing size of this compartment, indicating that birds preferred lower densities, an effect that became more pronounced with age. This effect occurred even when a barrier was used that had previously deterred 20-25% of birds from crossing to get to food after 6 h of food deprivation, suggesting that achieving a lower density was important to the broiler chickens. Since this methodology does not involve training, it could be used to evaluate the importance of spatial or other preferences in a wide range of domestic and nondomestic species. (c) 2010 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.