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Abstract
1. The objective was to determine the relation between social rank and use of resources in a small furnished cage with sufficient resources per hen (SF) and a commercial large one with less adequate allowance of facilities per hen (LF).
2. Ninety-two cross layers were used. At the age of 16 weeks, the hens were divided at random into two groups. There were 4 furnished cages with 5 birds per cage and 4 large furnished cages with 18 birds per cage. The dominance hierarchy was determined, in which highest, medium and lowest ranking hens in each cage were identified. Behaviour, use of facilities and physical conditions of these hens were measured (one in each rank category in SF, two in each in LF).
3. Dustbathing and litter scratching were more frequent in the high ranking hens than the medium and low ranked hens in LF, while no significant difference was found between them in SF.
4. No significant difference between SF and LF was found in use of nest boxes. However, pre-laying sitting tended to be less frequent in low ranking than medium and high ranking hens in LF (Social order × Cage design). In the nest box most of time was spent in pre-laying sitting by SF hens, LF high and medium ranked hens (average 94·9%). However, LF low ranking hens spent their time escaping (33·1%), pre-laying sitting (27·7%) standing (25·7%) and moving (13·5%) in the nest.
5. In the large furnished cages with less facilities per hen, high ranking hens may be expected to have priority using the dust bath. In contrast, low ranking hens rarely performed nesting behaviour fully, and spend more time using the nest box as a refuge than for laying.
Acknowledgements
This research was in part supported by a Grant-in-Aid for JSPS Fellows (no. 19-11909) from the Japanese Society for the Promotion of Science. We are grateful to the staff of Kanagawa Prefectural Livestock Industry Technical Center for technical assistance and their help. We also express special thanks to Dr M.C. Appleby and Assistant Editor Dr G. Baggott for improvements to this paper and for his help in publication.