Chief vets in Scotland, England and Wales have imposed a housing order on all poultry to protect flocks against the spread of avian flu by wild birds.
The order, which was widely anticipated by the industry, comes into force on December 14.
In the meantime vets are calling on keepers to use the next 10 days to prepare for the change in order to safeguard animal welfare and, where necessary, to erect additional housing.
The move follows the confirmation of a growing number of cases of avian influenza in both wild and captive birds and means it will be a legal requirement for all bird keepers to keep stock indoors and to follow strict biosecurity measures in order to limit the spread of the disease.
In a joint statement the chief vets said the rule applied to all birds, from the smallest to the largest flocks.
They added: “We have not taken this decision lightly, but it is the best way to protect your birds from this highly infectious disease.”
Last month major free-range egg producer Robert Chapman of Farmlay near Strichen said his industry was trying to cope without housing the birds for as long as it could because the maximum time free-range eggs can be rebranded as barn eggs is only 16 weeks, and producers also want to protect flocks during the wild bird migration in the spring.
The housing measures build on the strengthened biosecurity regulations that were brought in as part of the Avian Influenza Protection Zone (AIPZ) on November 11.
The AIPZ means that all poultry and captive bird keepers need to take extra precautions, such as cleaning and disinfecting equipment, clothing and vehicles, limiting access to non-essential people on their sites, and workers changing clothing and footwear before entering bird enclosures. Keepers are also asked to minimise contamination from manure and slurry and to use effective vermin control.
The Scottish Government said it had worked closely with the UK and Welsh Governments to introduce the new housing measures at the same time, meaning that the restrictions will be applied across the whole of Great Britain.
