When you hear “portholes,” cows likely don’t come to mind—but for decades, scientists have installed plastic-ringed holes called *cannulas* in cows’ stomachs to study digestion. “The procedure allows scientists to insert or remove material from the cow’s rumen…without having to repeatedly sedate or operate on the animal.”

First used in the 1920s, this method helps researchers analyze how cows process food to improve feed efficiency, boost milk production, and cut emissions like methane. It’s seen as a tool for making agriculture more sustainable.

Despite its benefits, the practice sparks strong ethical concerns. Animal rights group L214 calls it an “unfair system,” citing the invasive nature of the surgery. Still, researchers argue cows with portholes often live longer—up to 12–15 years—and return to normal life after 4–6 weeks of recovery.

Alternatives like lab-based fermentation models are emerging, but many scientists believe direct access to a live cow offers insights that machines can’t yet replicate.

At times, these cows are even displayed at fairs, letting visitors reach into their stomachs—an act critics call exploitative. The practice continues to stir debate about where science should draw the line in treating animals.

Would you like a visual to go along with this summary?