�Bird welfare can be affected by the type and size of the cage, the hygiene and temperature of the shed and the number of birds in the cage,� she said.
�While cages provide a very barren physical environment which restricts a hen�s freedom to move and flap her wings, alternatives such as free-range systems may be associated with other welfare issues such as higher mortality, vent pecking and significant risks to diseases like bird flu.�
Dr Collins said a lot of research was still needed to determine the best housing options for Australian hens, but suitable conditions are those that provide hens with their daily needs and provide good health and welfare.
�Good housing systems should ensure birds have good physical health, low mortality and low stress,� she said.
�It is often not the physical housing itself, but the way it is managed that determines how well the hens cope.
�Birds that can satisfy their behavioural needs, such as laying eggs in a nest and being able to dust bathe are generally considered to be less stressed.�
Dr Collins said ideally chickens would not be kept in cages at all.
But this had to be weighed up against the public�s requirement to have a supply of fresh, healthy eggs at a reasonable cost and the egg producers� need to manage large numbers of birds in a way that guarantees their health and protects them from environmental extremes and predators.
�In the European Union, the conventional or battery cage is now banned and has been replaced by an enriched cage that is bigger and contains a nest box, a perch and a scratching area which allows the bird to express its natural behaviour,� she said.
Dr Collins said more research was needed to compare the welfare of chickens housed in different systems, in order to provide best-practice advice to our producers and inform the community about what these provisions mean to the hens themselves.