Veterinary schools, veterinary hospitals, and bovine farming operations in North America often keep a healthy fistulated cow as a microbiota donor. Large animal veterinarians will pull the contents by hand from the healthy cows rumen system to help repopulate the fauna in a sick cows rumen. This process is called transfaunation, or a microbiota transplant.
In Europe, the fistulation of cows to provide rumen contents for transfaunation is considered unethical, and is not practised. Instead, rumen liquor is aspirated through a rumen-fluid collector, consisting of a Frick gag and a flexible hose with a perforated metal tip which serves as a filter.  The hose and tip is passed through the gag and down the oesophagus to the rumen.  It is normally possible to aspirate five litres of rumen liquor using this device.
Rumen contents from a fistulated cow can also help sheep and goats, which have similar digestive systems.
A 2014 review of rumen transfaunation research indicated that the procedure has been demonstrated to help correct indigestion resulting from illness, surgical correction of displaced abomasum, and ingestion of toxic plants.