Battery Hens Campaign: Background Information What Alternative Systems Are Available?
Perchery (Barn) and Aviary Systems It is ironic that such systems are assessed and evaluated by scientists and legislators as possible 'alternative systems' to battery cages, and often judged not yet sufficiently developed/perfected to enable battery cages to be banned. Yet during the first half of the century, egg laying hens were kept predominately in small free range flocks or barn systems! Now, such systems are measured taking into account economic criteria, and similar economies are sought as can be achieved with battery systems (with their economies of scale deriving from intensification). It is clear that animal welfare must be improved in alternative systems. There is scope for improvement, and major advances could be made if the recommendations of the UK's Farm Animal Welfare Council minority report on the welfare of laying hens in colony systems was implemented (December 1991). In particular:
There has been much debate recently about 'enriched cages', which seek to modify battery cages in order to overcome their most severe welfare problems. These range from the early 'Get-Away Cage' designed by Elson to more recent Modified Enriched Cages designed at Edinburgh, UK. Commonly, such cages have slightly more space and height than battery cages and incorporate nest boxes, abrasive strip, perches and dust baths. However, despite these modifications, enriched cages still fail to provide the space necessary for hens to perform most normal behaviours, such as wing flapping, walking, running and flying. Furthermore, this continued restriction on locomotion will mean continued problems with bone weakness. There are also problems with aggression, hen inspection, water accessibility, and practical problems such as egg collection, and dirty/cracked eggs. CIWF's report 'Beyond the Battery' - A Welfare Charter for Laying Hens deals with the question of modified enriched cages in some detail (See Battery Hen Campaign - resources available). It is not, therefore, proposed to repeat that work here. However, World Animal Net shares the opinion expressed in CIWF's conclusions that 'the potential for high welfare standards for laying hens will not be realised by the piece-meal approach adopted in the development of enriched cages'. There can be no doubt that non-cage alternatives provide the best way forward for the long-term benefit of the welfare of laying hens. It is, therefore, counter-productive and wasteful in terms of time and expense to attempt to retain the present system with minor enhancements.
Deep Litter SystemsThis is a flock system under which the hens are kept in a building (usually environmentally controlled). The floor is usually partially covered with litter (such as wood shavings or straw) with a raised perforated floor area (e.g. slats or wire mesh) over a droppings pit or manure belt. Birds are kept at floor level in these systems, and no perches are provided. EU egg marketing legislation (1274/91) provides a maximum stocking density of 7 birds/square metre, a minimum of one third of available floor area to be covered with litter and a 'sufficiently large' area for droppings collection.Deep litter systems can show an increase in the incidence of endoparasites and ectoparasites due to access to droppings. Coccidiosis is a regularly occurring parasitic condition in all litter systems, unless there is routine vaccination. Where large colony sizes are used, feather pecking and cannibalism can occur, and birds may be de-beaked. However, the environment in deep litter systems can gives hens freedom of movement and the opportunity to perform a large range of natural behaviours. This increased activity helps to improve bone strength. Nest boxes, perches and dust baths can be provided in deep litter of eggs The deep litter system is in widespread use for breeding and fattening birds, so is generally acceptable to the poultry industry. Deep litter systems are popular in the Netherlands, with about 15% of eggs being produced in these systems.
Perchery (Barn) and Aviary SystemsThese are also flock systems under which the hens are kept in a building (usually environmentally controlled). However, barn or aviary systems include perches and/or tiers of floors/platforms at different levels. Sometimes an area of the floor surface is littered. The perchery has developed from the deep litter system, adding different level perches. The aviary (or voli(re) has extra floors (if wire or slats) with feeders, drinkers and nest boxes on each floor.EU egg marketing legislation (1274/91) provides a maximum stocking density of 25 birds/square metre of available floor space, and at least 15 cm of perch space per bird. With perchery and aviary systems, the multi-tier environment and use of perches enables greater use to be made of available space. Also, birds can escape aggression by free movement within the house. However, similar problems occur as in deep litter systems. Also, injuries can occur when birds fall between levels or fly into platforms or furniture. A condition called bumblefoot also increases in such systems, and appears to be dependent upon the type of perches uses (form and material). There can also be practical problems, connected to observation, soiling from perches and depopulation. Early aviary systems suffered from severe aggression problems, but later systems, such as the Swiss voletage, Dutch tiered wire floor and Danish Hans Kier system have low aggression levels. A variation of such systems is the covered strawyard (Sainsbury 1981), which houses small groups of about 200 hens on deep straw, with separate feeders, drinkers, perches and nest boxes. They have freedom of movement, ability to perform many behaviours and activities, and feather pecking is rare. However, welfare problems can arise through increased incidence of disease and parasites. Also, egg collection can be time consuming when hens lay outside egg boxes.
Free Range SystemsHens in free range systems can be housed in deep litter, perchery or aviary systems, but must have day time outdoor access. EU egg marketing legislation (1274/91) provides that the requirements of perchery/aviary systems must be met, and that the birds must be provided with continuous day time access to land mainly covered by vegetation. A maximum stocking density of 1,000 birds/hectare is stipulated for the outside run.Free range systems provide birds with free movement, access to range, freedom to graze, and freedom to perform a wide behavioural repertoire, including dust bathing. (Most hens use the opportunity to walk, wing flap, scratch, peck and interact socially: Broom). It is clear that well managed free range systems have a high welfare potential. However, there can be problems of predation, worm infestation and Coccidiosis. Expert management is essential, with an effective system of grazing rotation and house movement (small, moveable hen houses can be used for this purpose). Well insulated and ventilate housing is necessary to protect hens against inclement weather.
Housing
Physiology
Ethology
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