The surge in popularity of backyard chickens could pose a risk to commercial flocks, experts say.
Research from the Royal Veterinary College revealed some chicken-keepers have a lack of disease knowledge and awareness of laws.
Leading EU poultry spokesman Charles Bourns says owners should read up before bringing a flock in to the garden.
"The industry isn't criticising people who keep hens in their gardens but there could be a risk of disease being transferred," said Mr Bourns, who chairs the EU Commission's poultry advisory group and farms 65,000 broiler hens at Charfield near Wotton-under-Edge.
"It's like having any other animal, you need to find out what you are getting in to."
He said that in Northern Ireland, owners must register just one bird but in the rest of the UK, registration with Defra is required for 50 or more birds.
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