Modifying the Cage to Accommodate Behavior

Conventional cages for laying hens (battery cages) have many disadvantages for behavior but also advantages: aggression and cannibalism (or the need for beak trimming to prevent these) are usually less than in other systems. Enriched cages reduce the disadvantages while retaining the advantages. The Edinburgh project on modified cages recommended increased area and height compared to conventional cages, and inclusion of a perch, a nest box and a dust bath. Collaboration with groups in England and Sweden followed and in 1999 the new European Union Directive on welfare of laying hens was passed, which will phase out conventional cages: all new cages from 2003 and all cages from 2012 must provide 750cm2/hen, nest box, perch and a litter area for scratching and dust- bathing. This will result in improvements in welfare, and more reliably so than by introducing other alternative systems such as percheries and free range. It is likely that most EU egg producers will adopt enriched cages in the medium term.

Introduction

Although they impose many restrictions on behavior, laying cages also have advantages for the behavior of hens. For example, aggression and cannibalism (or the need for beak trimming to prevent these) are usually less than in other systems, benefiting both the birds and the farmer. Projects in Edinburgh and elsewhere set out to reduce the disadvantages while retaining the advantages (Appleby, 1993; Sherwin, 1994). This paper will discuss the development and current status of enriched cages, their advantages and disadvantages for hens and producers and their future prospects.

The Edinburgh Project

Our project in Edinburgh adopted a stage-by-stage, systematic approach to cage design, in a series of trials that examined facilities separately, to consider their use by the birds and their effects. It concluded by recommending increased area and height compared to conventional cages, and inclusion of a perch, a nest box and a dust-bath. These prevent many of the behavioral problems of conventional cages – problems for farmers, birds or both. Welfare is improved, and more reliably so than in other alternative systems such as percheries and free range.

A final design was produced, for 4 or 5 birds, designated the Edinburgh Modified Cage (Appleby and Hughes, 1995; Appleby, 1998). There were several trials of this design in Edinburgh, with few production problems and with benefits for behavior and welfare compared to conventional cages. For example, mortality was extremely low, with no cannibalism ever recorded in modified cages.

International Development

Collaboration with groups in England and Sweden followed (Appleby et al., 1994; Abrahamsson et al., 1995) and in 1997 Sweden passed legislation requiring all cages to be enriched; enriched cages are now being introduced there, produced by a Swedish company (Ragnar Tauson, personal communication). Other cage manufacturers are also developing models.

On 15th June 1999 the new European Union (EU) Directive on welfare of laying hens was passed, which will phase out conventional laying cages (battery cages) by 2012. It is likely that this development was seen as acceptable because of the availability of enriched cages as an alternative. The requirements of the EU Directive are similar to the recommendations of the Edinburgh and Swedish projects: all new cages from 2003 and all cages from 2012 must provide 750cm2/hen, nest box, perch and a litter area for scratching and dust-bathing.

Practical Implications

Egg production costs more in enriched than in conventional cages, because of capital, labour and materials such as litter, but still less than in other systems such as free range. The selling price of eggs will increase; this is a matter of concern for consumers, but only partly offsets the considerable decline in price that has occurred over many years and is unlikely to reduce sales significantly. Design problems remain, particularly with the litter area, which needs a door to exclude birds during the nesting period and should preferably allow automatic provision of litter. However, such problems can and will be overcome.

Whether enriched cages will be a prevalent system of production in the long term is unclear; one factor that could affect this is progress in producing strains of birds that do not show cannibalism (Craig and Muir, 1996; Jones and Hocking, 1999), which would increase the viability and welfare status of non-cage systems. Meanwhile it is likely that most EU egg producers will adopt enriched cages in the medium term.

The modifications considered here do not all have to be adopted together. For example, if the cage area is increased and a perch is added, birds have more freedom of movement, show more synchrony of behavior between individuals, roost on the perch both in the day and at night, are more settled and are likely to show less fearful behavior. Nest boxes allow normal nesting behavior, restriction of which has been emphasized as one of the major problems in conventional cages, and are easier to provide than dust- baths.

Some of these modifications could be introduced at relatively little cost to producers and yet have significant impact on behavior and welfare of hens. It is therefore to be hoped that they may be considered in countries outside the EU and not subject to its legislation.

Acknowledgements – The Edinburgh project on modified cages was supported by the UK Ministry of Agriculture, Fisheries and Food.