Battery Hens Campaign: Background Information Battery Cages - The Welfare Problems
FAWC also recognised that good stockmanship is vital to good welfare, and concluded that those in charge of livestock should practice:
These measures of welfare will be considered in relation to battery hens. 1. Freedom from thirst, hunger and malnutritionIn most battery systems, hens would be given constant access to fresh water through drinkers, and feed would be provided regularly and usually conveyed automatically. However, with such automation, major problems can occur with equipment failure/malfunction. For example, drinkers can become blocked or entire systems fail. Also, sometimes crowding can prevent birds from reaching drinkers and feed temporarily. In a barren environment like the battery cage, deprivation of food and water tends to cause more stress and frustration to birds than would be the case in richer environments.Induced moulting can also cause hunger and thirst, when quantity/quality of feed are reduced. See Life of Battery Hens. In the UK, it is now illegal to keep laying hens without food for such periods, but a similar effect can be achieved through the sudden change of the hens' diet. Hens are wary of new foodstuffs, and this can lead to refusal to eat for a period, causing hunger. In nature, hens take varied diets. They also tend to eat grit. In battery cages, they are fed routine formulations, and given no grit. It is not clear, however, whether this leads to hunger, boredom or behavioural deprivation. However, concern has been expressed that the high incidence of osteoporosis could indicate a lack of calcium, phosphorus and Vitamin D, and that lack of animal protein could exacerbate pecking and cannibalism and affect plumage quality.
2. Freedom from discomfortDiscomfort can be caused to hens by environmental factors such as temperature and humidity, ventilation, dust and gas levels, litter quality/absence and lighting. Inside battery cages, temperatures are regulated using heating and/or ventilation. Serious problems can be caused by power failures, unless plants have emergency generators or other emergency provisions. Severe chilling or overheating is more common when the hens are removed from the units, for example, during transport for slaughter - where heat stress or chilling can be experienced. At low temperatures, reduced ventilation can lead to an build-up of dust or ammonia (which are respiratory irritants) in units.Dim lighting is regarded as an environmental deprivation for hens. Industry practice tends to restrict light intensity at feed troughs to a maximum of 35 lux (achieving just 5 lux at the darkest trough level), mainly to avoid higher intensities which they believe increases the risk of pecking and cannibalism. However, it is possible to keep hens in daylight when there is sufficient environmental stimuli. With regard to the welfare of laying hens in colony systems, the Farm Animal Welfare Council (FAWC) 's 1991 minority report recommended that the littered floor area and food troughs be well lit, (with lighting levels of more than 200 lux). Lighting should also be even, to prevent problems such as localised crowding. Seriously reduced or extended periods of 'daylight' can also cause discomfort to the hens, for example, as in the use of reduced daylight period for forced moulting. Serious physical discomfort can result from the practice of beak trimming (debeaking), which is prevalent in intensive systems. The beak is a complex sensory organ, with a sensitive nerve supply. It is believed that the debeaking not only causes acute short-term pain (when the beak is cauterised with the heated blade), but can also cause long term chronic pain (as evidenced in behavioural changes, such as inactivity, increased sleeping and modification of certain activities using the beak). Feather pecking is another common cause of pain and discomfort amongst intensively housed birds. Cannibalism is more common amongst intensively-housed birds not kept in cages. The small area allowance and low ceiling in battery cages are likely to cause discomfort. This cramped space leaves hens unable to stretch or extend their wings or exercise (see freedom to express normal behaviour below), leading to discomfort and even physical damage (bone weakness etc.). Discomfort can indicate uneasiness of the mind, as well as the body. In this regard, birds will experience discomfort when intensive housing conditions do not allow for 'personal space'. Increased population density causes birds to encroach into the personal space of others, which may result in stress, hysteria and social strife. It is also likely that they experience discomfort when they cannot nest build, as hens have a powerful motivation to build nests in which to lay their eggs (and the same is true of dust bathing, to a lesser extent). Birds can experience both stress and physical discomfort on capture and transportation. They are dragged from their cages by the legs, and carried (sometimes four from each hand) into packing crates. They can be unused to human contact. Then they are transported in the elements (after their environmentally controlled and dimly lit shed). Pre-slaughter handling can also cause discomfort, particularly the practice of shackling birds upside down on the slaughter line.
3. Freedom from pain, injury and diseaseDebeaking (see Life of Battery Hens) is a painful injury deliberately inflicted by humans in an attempt to 'adapt the bird' to intensive systems. It is done in both cage and floor housing systems.Skeletal weakness can be caused by high levels of egg production. Bone weakness is also caused by restricted cage conditions (restricting exercise and movement, including wing flapping). This leads to bone breakage's in up to 30% of birds during capture and transportation . Removal from cages exacerbates this problem (particularly when cages have restricted or rough openings). There are around half as many broken bones in birds from free range systems (Gregory et al. 1990). Shackling upside down for slaughter will cause further injuries for birds with leg weaknesses. Injuries can be caused by pecking (see above), and feathers removed or wounds caused. Foot and claw damage is more frequent in cages than in other systems, with lesions, fissures and overgrown, twisted or broken claws (Tauson 1980). Also, the soles of the feet can be damaged through pressure on the thin wire floor of cages. Claws can grow too long (with nothing to wear them down) and be prone to damage. (Thus, the compulsory abrasion strip in Swedish cages, where hens food-scratch and wear down their claws). Battery hens are prone to develop tumours of the oviduct, coinciding with selection for higher egg production (Angum et al 1989). Diseases which affect battery hens include Marek's disease (a form of cancer), Newcastle's disease, bronchitis, avian rhintracheitis, avian encephalomyelitis and infectious bursal disease. Hens also suffer from metabolic disorders, impacted eggs, prolapses and disorders of kidneys and liver are common. Routine vaccination is given to counter most infectious diseases. However, when problems do occur, it is easy for injured or diseased birds to be overlooked in cage systems. Endoparasites are treated routinely, but there is an increasing problem with mite infections.
4. Freedom to express normal behaviourThe environment of a battery cage clearly does not give hens the freedom to express normal behaviour. Indeed, battery cages prevent hens from performing very important behaviours, such as:Furthermore, they do not even provide birds with the space needed for basic movements, as set out in the principle elaborated by the UK government's Brambell Committee (1964) that 'an animal should at least have sufficient freedom of movement to be able without difficulty to turn round, groom itself, get up, lie down and stretch its limbs'. Such restriction in movement causes physical problems, such as bone weakness, as well as behavioural problems (stress/frustration). Restricted space also prevents birds from carrying out 'comfort behaviours,, such as wing flapping, shaking and stretching, and from having necessary 'personal space' and the ability to retreat from aggressors.
NestingHens are highly motivated to find/make a nest in which to lay their eggs (Dawkins 1983). Recent studies have shown that hens will work to gain access to a nest site (Cooper & Appleby 1993), as well as to food. Deprivation of this pre-laying nesting behaviour may be one of the most important in terms of welfare: 'it is widely accepted that frustration of nesting is the most severe behavioural problem of hens in battery cages'. (Appleby et al).
PerchingWhen conditions permit, hens seek perches to roost upon at night. Before sunset there is much activity when birds compete for perch places (with the primate sites being the highest) (Fraser & Broom 1990). The welfare of birds is likely to be impaired if this perching behaviour is frustrated. Inability to perch has physical as well as behavioural consequences, as perching improves leg strength.
DustbathingDustbathing is performed to improve plumage condition, and rid feathers of skin, mites, dirt, excess oil etc. Birds are motivated to dustbathe, and even attempt to dustbathe on wire cage floors ('vacuum dustbathing) if frustrated. When birds are permitted to dustbathe, aggressive pecking decreases (Vestergaard 1989).ForagingHens are also motivated to scratch and forage for food. In natural conditions, they may spend much of the day foraging. This behaviour is frustrated in battery cages, which can lead to abnormal/misdirected behaviour (feather pecking).
Space needed for basic movementsArea used by medium hybrid hens (Dawkins & Hardie 1989) for different behaviours:
Note that this is the space used, and not the space needed for the birds to perform these actions comfortably (which would always be greater). This should be compared to the standard space allowance of 450 sq. cm per bird in a battery cage. 5. Freedom from fear and distressFear and distress can arise from many of the conditions described above. Increased aggression, and the impossibility of birds escaping from this, are particular problems. Also, due to being raised in cage conditions, battery hens can be particularly timid of novel stimuli, such as humans, unexpected noise or movement, changes in groups/mixing etc. This can lead to hysteria, and can make events such as removal from cages, transport, and slaughter particularly distressing for caged birds.
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