Advantages and disadvantages of different housing systems for the welfare of laying hens

Disadvantages in all systems
There are some management practices or conditions that reduce welfare in all or most systems and they include the following:

Conventional cages
The evidence from this report has in the main substantiated previous scientific knowledge that the welfare of laying hens is severely compromised in conventional cages (for example, see review by Baxter, 1994).

Furnished cages

Non-cage systems

Increased space availability can give submissive hens the opportunity to avoid aggressive birds.

Overall welfare impact

With the exception of conventional cages, we conclude that all systems have the potential to provide satisfactory welfare for laying hens. However this potential is not always realised in practice. Among the numerous explanations are management, climate, design, different responses by different genotypes and interacting effects. For example there was different use of nestboxes in furnished cages by different genotypes. The design of small furnished cages also had a significant impact on dustbath use.

All cage systems tend to provide a more hygienic environment with low risk of parasitic disease. There is possibly a high risk of poor welfare on a flock basis in all systems with larger group sizes (above approximately 10-15 birds) from damaging pecking and cannibalism. All laying hens also are at high risk from sustaining fractures both during the laying period and at depopulation. There is evidence that both these problems are associated with genetic selection for high productivity. Some existing genotypes (mainly white feathered) show a lower tendency for damaging pecking. Much greater emphasis should be placed on selecting genotypes with reduced damaging feather pecking tendencies for use in alternative housing systems for laying hens. Recent studies have shown that bone strength can be improved in laying hens by selection over only one or two generations without a great decrease in productivity (Fleming and others, 2005). For good laying hen welfare it is a priority that action be taken to reduce the current unacceptable level of fractures sustained during the laying period in all systems apart from conventional cages. This is likely to involve a combined approach of selective breeding, plus refinements to design and management including lighting.

Conventional cages do not allow hens to fulfil behaviour priorities, preferences and needs for nesting, perching, foraging and dustbathing in particular. The severe spatial restriction also leads to disuse osteoporosis. We believe these disadvantages outweigh the advantages of reduced parasitism, good hygiene and simpler management. The advantages can be matched by other systems that also enable a much fuller expression of normal behaviour. A reason for this decision is the fact that every individual hen is affected for the duration of the laying period by behavioural restriction. Most other advantages and disadvantages are much less certain and seldom affect all individuals to a similar degree.