In the barn system hens are able to move freely around the house. The EU Welfare of Laying Hens Directive stipulates a maximum stocking density of 9 hens per square metre of useable floor space. Perches for the hens must be installed to allow 15 centimetres of perch per hen. Litter must account for one third of the ground surface. This is used for scratching and dust bathing.
One nest box per five hens or communal nests, at the rate of 120 birds/m² of floor area, is provided. Linear feeders provide at least 10 cm per hen, or circular feeders provide at least 4 cm per hen. There is also plenty of drinking space per hen. Water and feeding troughs are raised so that the specially prepared food is not scattered. Electric lighting is provided to give an optimum day length throughout the year. At the end of the laying period the house is completely cleaned and disinfected.
Many barn houses in the UK are a single level part-litter, part-slatted floor. In this system, the EU Welfare of Laying Hens Directive allows a maximum stocking density of 9 hens per square metre.
Additional requirements of the Lion code
The Lion Quality Code of Practice stipulates that there is a maximum colony size of 6,000 birds.