Shimmura, 2008 – Pecking behaviour of laying hens in single-tiered aviaries with and without outdoor area

1. The objective of the present study was to examine the behaviour of laying hens in single-tiered aviaries with and without outdoor areas with particular reference to the proportion of each behaviour and the ways it changed.
2. In all, 144 interbred cross layers (WL/RIR cross-breed) were used. At the age of 16 weeks, the hens were divided at random into two groups and moved to single-tiered aviary (SA) and free-range systems (FR, SA with in addition an outdoor range area covered with clover) with 18 hens per pen. Behavioural observations were conducted before, during and after access to the range.
3. All behaviours using the beak (eating, grazing, drinking, preening, aggressive pecking, feather pecking, litter pecking, object pecking and mate pecking) were recorded as pecking behaviour.
4. While most of the FR hens spent their time outside foraging, the proportion of hens eating,
preening, litter pecking, object pecking, aggressive pecking and feather pecking was higher in SA than in FR hens.
5. The proportion of hens performing pecking behaviour of all types was very similar in SA (61.7±2.0%) and in FR (64.0±0.8%). The proportion of hens performing overall pecking behaviour increased as pre-laying sitting decreased.
6. The proportion of hens feather pecking decreased in FR during access to range and a similar tendency was found for aggressive pecking.
7. In conclusion, the total proportion of hens pecking was almost the same regardless of whether an outdoor area was provided or not, but the incidence of different types of pecking behaviour differed between SA and FR. The risk of feather pecking in FR may be lower when an outdoor grazing area is provided, although further testing on a larger scale would be essential.