Hole-y Cow! These cows have been given a fistula, a hole directly into the stomach that scientists can reach into and study to see how certain foods get digested. Through this kind of work, better food can be concocted and studies into stomach cancer and other problems can be conducted. Although it looks inhumane, the cows don’t seem to mind. Animals can live a surprising amount of time with a permanent hole to their stomach, especially if it is a surgically made fistula. Nowadays, agricultural scientists learn about the digestive system of cattle by putting holes in cows – and the cows stay alive and well. These cows (fitted with a sealing cover called a “cannula”) each have a hole into their stomach. Through this hole one can extract food caught mid-stream through the digestive system. Take a look at this bizarre thing.
Source : http://www.weirdpalace.com