ORIGINAL ARTICLE Differences of behavior, use of resources and physical conditions between dominant and subordinate hens in furnished cages Tsuyoshi SHIMMURA, Yusuke EGUCHI, Katsuji UETAKE and Toshio TANAKA Graduate School of Veterinary Medicine, Azabu University, Sagamihara, Japan ABSTRACT The objective of the present study was to search for differences in the behavior, use of resources and the physical condition between dominant and subordinate birds in furnished cages. In total, 60 commercial White Leghorn layers were used. At the age of 54 weeks, these birds were divided into two groups. Each group consisted of six cages with four birds per cage and six cages with six birds per cage. The dominance hierarchy was measured, to identify the highest dominant bird and the lowest subordinate bird in the hierarchy of each furnished cage. Behavioral observations using scanning techniques at 10 min intervals were conducted on the birds at 57 and 67 weeks of age for 3 days, respectively. Their physical condition (bodyweight and claw length) was also measured. Dominant birds used the dust bath more (P < 0.1) and nest box less (P < 0.01) than subordinate birds did. The use of the nest box decreased for subordinate birds from 57 to 67 weeks of age (P < 0.05). The dominant birds performed aggression and exploring more frequently than the subordinate birds (P < 0.001 and P < 0.05, respectively). In the comfort behaviors, the dominant birds performed dust-bathing, as well as the using the dust bath, more than subordinate birds did (P < 0.1). In their exploring behavior, including scratching and litter pecking, dominant birds performed both behaviors more frequently, as well as using the dust bath and dust-bathing in it, than subordinate birds did (P < 0.1 and P < 0.05, respectively). Aggression decreased for dominant birds from 57 to 67 weeks of age. In contrast, eating (P < 0.1) as well as drinking (P < 0.1) and other comfort behaviors (P < 0.1) increased for subordinate birds from 57 to 67 weeks of age. There was no significant difference between dominant and subordinate birds in their physical conditions. In conclusion, dominant birds had priority to use the dust box compared with the subordinate birds in the furnished cages. Conversely, the subordinate birds stayed in the nest box more than the dominant birds did. In the furnished cages, equipping the nest box was important not only for the birds to perform nesting behavior, but also for the subordinate birds to use the facility as a refuge especially just after introduction to the cage. Key words: behavior, dust bath, furnished cage, hierarchy, laying hens. INTRODUCTION The use and development of different housing systems for layers have been changing in the world. Conven- tional cages will be banned in most of Europe in 2012, although the vast majority of layers in the world are still kept in cages. Different alternative housing systems for laying hens have been developed. The most common housing systems comprised deep litter, aviaries and, more recently, furnished cages. Fur- nished cages will be the only legal form of cage in the EU from 2012. Today, about 40% of layers in Sweden are kept in furnished cages (Tauson 2005). Other countries where this system is used are mainly the UK, Norway, Germany and Denmark. According to the 1999 EU directive, only these cages will be allowed Correspondence: Toshio Tanaka, Graduate School of Veteri- nary Medicine, Azabu University, Sagamihara, 229-8501, Japan. (Email: tanakat@azabu-u.ac.jp) Received 10 March 2006; accepted for publication 1 Septem- ber 2006. Animal Science Journal (2007) 78, 307–313 doi: 10.1111/j.1740-0929.2007.00440.x © 2007 The Authors Journal compilation © 2007 Japanese Society of Animal Science