Mortality
The main welfare risks in cage-free systems are the transmission of infectious diseases and severe feather pecking, both of which can lead to mortality. Severe feather pecking is a significant welfare problem where birds vigorously peck at and pull out the feathers of other birds. These issues, and the extent to which they occur, are largely affected by the management and stockpersonship on each farm. Addressing severe feather pecking requires an integrated approach comprising genetic selection, the provision of appropriate housing conditions, and good management. The University of Bristol has developed a management guide for severe feather pecking for producers: ‘FeatherWel’ available here http://www.featherwel.org.
Birds in non-cage systems tend to have higher mortality than those in cage systems where weekly mortality is generally less than 0.1%. However, a study [1] of the effect of cages and alternative housing systems on a number of bird production and welfare parameters found that mortality or feather pecking did not differ between systems. This means that the chance of a feather-pecking outbreak is the same regardless of housing system. Mortality can be higher in non-cage systems because a severe feather-pecking or infectious disease outbreak can have greater consequences due to transmission throughout large groups of birds. In order to reduce mortality in non-cage systems, infectious disease and the risk of feather pecking must be managed better.
Pests parasites and disease
The transmission of infectious diseases is strongly affected by biosecurity and health management practices. Causes of mortality may also include bacterial infections (erysipelas, colibacillosis, pasteurellosis) that result from birds having contact with soil on the range or the litter in the shed, and viral diseases (lymphoid leucosis, Marek’s disease, Newcastle disease). 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 improved management of these systems. A Swiss study[3] that monitored hens for 12 years after cages were banned in Switzerland, found that the 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, birds must be monitored and treated promptly for mites [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. Shed and range 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 also help deter ground predators. Providing overhead cover – either natural or artificial – will protect hens from aerial predators while still encouraging birds to access the range.
Summary
Overall, management is a very large determinant of welfare in cage-free systems. There are advantages and disadvantages to hen welfare in each type of housing system. The main risks to hen welfare in cage-free systems are, at present, highly variable. Many of the disadvantages in cage-free systems may be addressed and improved by good infrastructure design, good management practices, genetic selection, and further research. Conversely, the welfare issues in battery cages are inherent to the system, are therefore largely not affected by management and thus cannot be avoided.
To find find out more about the science of battery cages and alternative systems read RSPCA’s scientific report here, and lend your voice to the RSPCA’s campaign against battery cages here.
[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.
