Layer Housing

Farmers want their birds to be in the best shape possible and strive to care for them as best they can, using the equipment, technologies, and knowledge available to them. Selecting a production system and housing design is a complex, multi-factorial issue that requires great consideration. The issue of cage systems vs. cage-free is not as simple as some would like to think. Let’s take a look at why.

Chickens are kept in barns to protect them from harsh weather, disease, and predators. Laying hens, in particular, are raised to produce eggs and are often kept in cages with mesh flooring that allows manure to fall through. Conventional laying cages, which have also been called battery cages, have been criticized for providing a barren environment to birds leading to abnormal hen behaviour (1). Conventional cages were banned in Europe in 2012 (2), however, 95% of layers in the US remain in conventional cages (4). This is because, from an economic standpoint, conventional cages have low production costs with a high degree of mechanization (e.g. egg production, quality, and efficiency). Nonetheless, this high degree of mechanization comes at the cost of welfare for laying hens. In the USA, conventional cages are designed to house 3 to 6 birds but, in commercial production, birds are often housed at 7 to 8 birds per cage (5). High densities restrict laying hens from performing their most basic behavioural requirements – nesting and roosting (5). Additionally, many natural behaviours (i.e. dust bathing) cannot be performed.

Research over the last couple of decades has been increasingly geared towards improving the welfare of birds in cages by altering cage design or considering cage-free systems (5). Although alternative systems have benefits to welfare (i.e. complex environment to fulfill behavioural requirements) compared to conventional cages, such systems still have considerable drawbacks in terms of animal health, biosecurity, and economic efficiency (5). It cannot be assumed that non-cage or free-run / free-range systems will improve the welfare of laying hens (5).

Furnished, or enriched, cages and alternative cage-free systems (free-run, free-range, or aviary) provide perches, nest boxes, litter for dust bathing, and more space per hen than conventional cages (2). This provides laying hens with the ability to express a wider range of natural and comfort behaviours such as stretching, wing flapping, dust bathing, and foraging (2,5). However, furnished cages and alternative cage-free systems have the potential to cause injury when hens miss the perch during flying, harbor disease vectors/parasites, or provoke aggression. Additionally, group size, freedom of movement, and the complexity of the environment affect the welfare of hens in furnished and alternative systems (2). Group size and freedom of movement are greater in alternative systems than in furnished cages, and the environment is more complex (2). However, with larger group sizes comes increased and more severe feather-pecking. Severe feather pecking results in feather damage and denuded areas. If these areas continue to be pecked it can lead to wounds and development of cannibalism (2). Once an outbreak of feather pecking or cannibalism occurs in an alternative system, it is very difficult to manage (2).

Thus, a decision needs to be made by producers, consumers, and regulators about how to balance the freedom to exercise and the ability of laying hens to perform natural behaviours against potential hazards. It is important to acknowledge the advantages, disadvantages, and risks for each system when making this decision.

Conventional Cages https://commons.wikimedia.org/wiki/File:Battery_hens_-Bastos,_Sao_Paulo,_Brazil- 31March2007.jpg

Furnished cage http://www.meristem.com/news_releases_fac/2013/2013_20_2a.jpg

Cage-free alternative system https://www.poultryventilation.com/sites/default/files/images/featured/layer–aviary.jpg

References

1. Barnett, J. L., Glatz, P. C., Newman, E. A., and Cronin, G. M. 1997. Effects of modifying layer cages with perches on stress physiology, plumage, pecking, and bone strength of hens. Aus J Exp Agric. 37: 523-529. doi: 1071/EA97024.
2. Rodenburg T. B., Tuyttens, F. A. M., and Sonck, B. 2005. Welfare, health, and hygiene of laying hens housed in furnished cages and in alternative housing J Appl Anim Welfare Sci. 8: 211-226.
3. Tauson, R. 2005. Management and housing systems for layers – effects on welfare and production. World Poultry Sci J. 61: 477-490. doi: 079/WPS200569.
4. Compassion in world farming. 2017. Welfare issue for egg laying hens. Available from: https://www.ciwf.com/farm-animals/chickens/egg-laying-hens/welfare- issues/ (Accessed 18 May 2017).
5. American Veterinary Medical Association. 2012. Literature review on the welfare implications of laying hen housing. Available from: https://www.avma.org/KB/Resources/LiteratureReviews/Documents/laying_hen_pdf (Accessed 19 May 2017)