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Why is it important for layer hens to express normal behaviours?
The ability to express normal behaviours is important to every hen whether they are housed in cage or cage-free systems. Hens in battery cages experience extreme behavioural restriction. They cannot flap or fully stretch their wings, walk or run, and do not adjust to this behavioural restriction. Further, hens possess a number of natural behaviours which they are motivated to perform such as foraging, perching, dustbathing and laying their eggs in a nest. None of these normal behaviours can be performed in a battery cage, leading to intense frustration and suffering.
Layer hens have a strong motivation to perform ‘nest building’ behaviour, which is triggered by hormones at ovulation. Prior to egg laying, hens perform pre-laying behavioural patterns which include searching for a nest site, nest building, and sitting on a nest. The need for layer hens to perform pre-laying behaviour and use a nest has been assessed by motivation tests, which have consistently demonstrated that it is a high priority. Hens have been found to work harder to access a discrete nest site prior to egg laying than they do gaining access to food following 4 hours of food deprivation. Further, an enclosed nest area can reduce cannibalism.
Why it is important for a hen:
If denied a nest, hens can become frustrated, pace, and retain their eggs beyond the expected time of lay. Abnormal behaviours include: increased clucking, pacing and going through the motions of nest building. Hens endure this frustration every day they are confined in battery cages.
Hens have demonstrated a strong motivation to access perches in behavioural tests, for example by pushing through weighted doors. The provision of perches allows hens to perform their normal perching behaviour, therefore satisfying a behavioural demand. Almost all layer hens use perches at night if adequate perch space is provided. Hens show signs of unrest when they are deprived of the opportunity to perch at night, and experience frustration and reduced welfare if perching is not possible.
The provision of perches:
The inability to perch decreases muscle and bone health. Rearing birds without early access to perches causes poor muscle strength, a lack of motor skills, and the inability to keep balance, with long-lasting effects on welfare. The inclusion of perches in all housing systems is relatively straightforward, and has the potential to give large improvements in welfare if placed and managed correctly.
Foraging is a key element of the normal behaviour of hens. When litter is available, it is used extensively by hens for scratching and pecking. Hens perform foraging behaviours even when feed is freely available in feed troughs, demonstrating an instinctive motivation to forage for food. In addition, studies have found that hens spend the majority of their time ground pecking and ground scratching if litter is available.
Foraging behaviour is not possible in battery cages, and is only partially accommodated in furnished cages. Environmental complexity is severely limited in cages, which limits the hens’ ability to explore their environment and forage.
Hens have an instinctive motivation to dust bathe. When they have access to soil, sand or litter, hens will dust bathe most days, often for long periods at a time. Dust bathing involves hens crouching down and using their wings to throw dust through their feathers before standing and shaking off the dust. Dust bathing cleans and maintains feathers, removes oil build-up, parasites, and helps regulate body temperature.
Hens are unable to dustbathe in battery cages. Caged hens will try and go through the motions of dust bathing even in cramped cage conditions. This is called ‘sham’ dust bathing, but it does not satisfy birds, and can indicate a reduced state of welfare. When hens are unable to dust bathe, their plumage is in a poorer condition as it is dirtier and less insulating.
Hens need space to stretch, preen their feathers, flap their wings and move around. Hens like to have space so they can chose where they spend their time.
Battery cages are so small that birds can't engage in simple, comfort behaviours like fully stretching and flapping their wings. Lack of exercise due to restricted space causes extremely weak bones and muscles which can result in fractures.
Good welfare requires not only the absence of disease, hunger, and thirst, but also the opportunity for hens to perform behaviours which they are motivated to perform. These behaviours include nesting, foraging, ground scratching, perching, and dust bathing. Sufficient space, perches, litter, nest boxes, and a varied environment give hens the freedom to exercise and carry out normal behaviours. The expression of these behaviours leads to better health and welfare. Preventing their expression leads to frustration, distress, and can create physical welfare problems.
Hens in battery cages suffer extreme behavioural restriction, and due to their inability to walk, flap their wings, or perch, they suffer the poorest bone and muscle strength of all housing systems and the highest number of fractures at the end of their lives.
Many scientific studies have concluded that good welfare for layer hens simply cannot be achieved in battery cages. To 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.
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