Two students and a visiting member of staff at a college were infected with a gastrointestinal illness.
The three at Shuttleworth College were struck down with cryptosporidium, which can cause diarrhoea. The disease is not uncommon in animals and is mainly found in cattle.
A college spokesman said: “The most important means of controlling the disease is through good hygiene.
“As a precautionary measure, we are restricting access to Kingshill Farm Yard to essential staff only for the next week or so. We have taken this action in agreement with the relevant authorities.”