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Can layer hen mortality, pests, parasites, disease and predation be managed in non-cage systems?

Article ID: 653
Last updated: 30 Mar, 2016
Revision: 2
Views: 188

Mortality

Causes of mortality in all egg-laying systems include disease, severe feather pecking and cannibalism. Birds raised in non-cage systems tend to have higher actual mortality levels than those in cage systems where weekly mortality is generally less than 0.1%. However, a study[1] of the effect of conventional cages and alternative housing systems on a number of bird production and welfare parameters, found that the risk of mortality or feather pecking does not differ between systems. This means that for an individual bird, regardless of the system in which it is housed, the chance of mortality or a feather-pecking outbreak is the same. One reason that actual mortalities are higher in non-cage systems is that a feather-pecking outbreak, for example, has far greater consequences simply because the feather-pecking birds have access to many more birds than just a few cage mates. So, in order to reduce mortality in non-cage systems, disease and the risk of feather pecking must be managed better.

Pests, parasites and disease

Causes of mortality may also include bacterial infections (erysipelas, colibacillosis, pasteurellosis) and viral diseases (lymphoid leucosis, Marek’s disease, Newcastle disease) that may result from birds having contact with soil on the range or the litter in the shed. Increased incidence of internal and external parasites may also be found in non-cage systems[2]. However, this does not mean that non-cage systems should be abandoned. Rather, the emphasis should be on managing such systems better. A Swiss study[3] that monitored hens for 12 years after cages were banned in that country, found that incidence of viral disease and parasitism consistently decreased over this period due to a focus on bird management. Intestinal worm burdens must be monitored and birds treated when high egg counts are detected. Similarly, mites must be monitored and treated promptly[4]. Bacterial disease also needs to be addressed, for example, through increased emphasis on managing air quality (dust) in sheds. Managing disease in non-cage systems requires using vaccines where available, thorough disinfection of sheds and equipment, paddock rotation, and implementing appropriate biosecurity measures.

Predation

Where hens have access to the outdoors, there is a risk of birds being predated upon by both ground and aerial predators. Managing this risk is key to reducing mortalities due to predation. Shed design should be such that predator entry is restricted. Similarly, where fencing is used, it should be constructed and maintained to prevent the entry of predators such as foxes and dogs. Guardian animals such as dogs (e.g. maremmas), alpacas or donkeys may help deter ground predators as well. Providing overhead cover – either natural or artificial – will protect hens from aerial predators while still encouraging birds to access the range.
 
[1] Freire R, Cowling A (2013) The welfare of laying hens in conventional cages and alternative systems: first steps towards a quantitative comparison. Animal Welfare 22:57-65.
[2] Lay Jr DC, Fulton RM, Hester PY et al (2011) Hen welfare in different housing systems. Poultry Science 90:278-294.
[3] Kaufmann-Bart M, Hoop RK (2013) Diseases in chicks and laying hens during the first 12 years after battery cages were banned. Veterinary Record 164:203-207.
[4] University of Bristol (2013) Improving feather cover: A guide to reducing the risk of injurious pecking occurring in non-cage laying hens, Version 1.2. FeatherWel: Promoting bird welfare, available at http://www.featherwel.org/injuriouspecking.

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Also read
document What are the RSPCA Approved Farming Scheme standards for layer hens?
document What is the RSPCA's position on battery cages for layer hens?
document What are barn-laid eggs?

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