Material & Methods

Animals & housing

The study used a total of 80 chicks, all of which had the same origin – a commercial hatchery in Sweden. However, only 40 of these were hatched at the hatchery, as the remaining 40 were hatched under controlled conditions at Linköping University. All eggs were incubated simultaneously and after hatching, the chicks hatched at the hatchery were transported to the university. After arrival, all chicks were weighed and provided with leg rings of different colors to make it easier identifying individuals during the upcoming tests. The chicks were then kept in cages together with other individuals of the same treatment group.

Procedure & experiment

In this study, four chicks from the same treatment group with the same leg ring color were placed inside enriched test arenas to examine the presence of play behaviors. During the tests, chicks were observed for 30 minutes twice a week, and to stimulate play and increase the occurrence of certain behaviors, novel objects were placed inside the arena after 10 and 20 minutes. The first test occurred when the chicks were 1 week old, and tests continued until the chicks had reached approximately 6 weeks of age. All tests were recorded, and data collection was done by noting behaviors while analyzing videos from the experiments.

The enriched test arena used in the play study.