A 3km exclusion zone has been set up after a suspected case of foot-and-mouth disease was found in Wiltshire.
The site of the suspected case is Little Buckholt Farm near Tytherley in south Wiltshire.
The exclusion zone means no livestock can be moved across, into or out of the marked area.
Tests are being carried out to determine whether the case is foot-and-mouth disease.
"Most farmers are well aware that we have to be very vigilant mainly and pick up on any sign of the disease and have it tested even if it proves negative, " said the National Farmers Union's Denise Plummer, who is also a Wiltshire farmer with livestock.
"We know not to travel from one farm to another, to keep our distance from fellow farmers in the zone," she said.
The government's chief vet is to ease some animal restrictions imposed after the outbreak of foot-and-mouth disease, despite a seventh case being confirmed.
From 1530 BST animals can be moved from farm to farm under licence in "low risk areas", but markets cannot be held.
However, restrictions remain in place in much of the south-east of England near to the Surrey outbreaks.