The Palace of Westminster has a blanket ban on animals
An MP has said he is "furious" at being banned from bringing a cow to the House of Commons.
Daniel Kawczynski, the Conservative MP for Shrewsbury and Atcham, wanted to take the animal to Westminster to highlight the problem of bovine TB.
He said the disease was causing farmers to go bust and planned to protest on the green outside Parliament over the government's handling of the issue.
But Commons officials said nearly all animals were banned from its grounds.
Only guide dogs, sniffer dogs and police horses are allowed.
Mr Kawcyzinski said: "I am furious that they are preventing me from highlighting the appalling situation of bovine TB in this country.
"Thousands of dairy farmers around England are going bust as a result of this appalling disease and the government is not lifting a finger to deal with the crisis.
"As chairman of the all party group for dairy farmers I wanted to bring a cow to the green outside parliament to demonstrate together with hundreds of farmers from around England."
The National Farmers' Union said the number of cases of bovine TB had risen by as much as 18% between 2006 and 2007.