A rumen fistula is a surgically created entry to the rumen in the left flank of the ruminant, typically permanent and with a rubber or similar material device (a 'cannula') fitted to close it between times of use. It enables the rumen contents to be accessed, and the rumen wall to be viewed and biopsied. Surgically modified ruminants such as these are only found on research farms, where they are used to study rumen function.

Looking in through the fistula, you can see the rumen contents and the rumen wall.

Rumen Denev has written:

'Posledno'

Rumen Danov has written:

'Zhiva stomana'

Rumen Petrov has written:

'Neshto nepreodolimo'

Rumen Trifonov was born on 1985-02-21.