So-called stomach windows serve to assist farm owners in Europe, allowing them to see exactly what’s going on with their cows.

Instead of high tech innovation, some European and American agricultural researchers are using an old method called a cannula to see exactly what’s going on inside the digestive system of their cows.

A hole, also known as a fistula, is cut into the anaesthetized bovine’s digestive tract, creating a circular window or porthole, so scientist’s can take a close look at the effect of different feeds on the animal.

After a cow is anesthetized and undergoes surgery to have the cannula inserted, he or she is given a set time limit to graze, before being examined. Once the period is up, researchers pull the cannula plug and stick their hands inside the opening to remove a portion of what the cow has been eating. It is said the animals cannot feel this process.

The partially digested material is analyzed to determine which feed provides the best results and energy efficiency.

The process has been around for well over a century, but animal rights activists are against it. Reportedly only used at research institutions, scientists claim the procedure can ultimately help to reduce the amount of methane gas released by the animals.