Cannulated cows, sometimes called rumen fistulated cows or ‘cows with windows’, have been used for research since the 1830s. These cows are surgically fitted with a cannula, a ‘window’ into the cow’s stomach, in the side of their abdomen. The cannula holds the side of the cow open permanently, allowing scientists to access the rumen, the largest of a cow’s four stomach compartments, and the bacterial colonies within the rumen that are vital for digestion.
In addition to monitoring the digestion process, healthy cannulated cows can easily be used as a rumen fluid donor for sick cows, a process called rumen transfaunation. Whether it’s because of antibiotics, surgery, toxins, or illness, a cow who has lost her healthy rumen bacteria cannot digest food or absorb nutrients, and will continue to decline in health. Transferring the rumen fluid from a healthy cow will reintroduce the healthy microorganisms into the rumen, building up the bacteria colonies needed for digestion, and allowing the sick cow to absorb nutrients properly.
Cannulated donor cows will ensure that healthy rumen fluid is readily available for transfaunation, and can be collected with little stress to the cow (compared to collecting rumen fluid via oral stomach tube from a cow without a rumen cannula).
Adhering to the following practices will help determine the success of the transfaunation process:
- The recommended volume of rumen fluid needed for transfaunation can vary. Speak to your vet for specific fluid volume recommendations for an individual cow’s requirements.
- Collected rumen fluid should be transferred to the recipient as soon as possible. Short-term fluid storage can be done safely if the fluid is stored at the cow’s body temperature and away from light.
- Rumen fluid from a healthy cow should appear yellow-brown or olive in color, based on diet. Rumen fluid that appears foamy or frothy should not be used for transfaunation.
- Ideally, rumen fluid should be collected several hours after feeding, or just prior to feeding. This ensures that the pH level of the fluid is around 6.0. Rumen fluid collected soon after eating will have a low pH level, and will result in decreased microbial activity. Rumen pH can be tested with pH paper.
- Recommendations for filtering or straining the rumen fluid prior to introducing it to the recipient cow can vary. Ask your vet for specific recommendations for your own cattle.
- DePeters, E.J., and L.W. George. “Collection of rumen fluid.” Progressive Dairyman.
- DePeters, E.J., and L.W. George. “Treating dairy cow indigestion with rumen transfaunation.” Progressive Dairyman.
- Haskell, Scott R.R. “Rumen fistula surgery for the private practitioner.” Yuba College Veterinary Technology Program.
- Podwirny, Lisa. “Transfaunation in Dairy Cattle: What is it?”