The post about the cow's digestive tract in sculpture reminded me of cannulated cows. Surprisingly, we've never posted about them before. The sculpture has to be a more pleasing sight, but researchers can watch a real cow digest food through a porthole.
In 1822, Alexis St. Martin was left wounded with a hole in his stomach, through which his doctor observed digestion and even did research on how foods digested. The hole is called a fistula. You can't just cut a hole in a living human to study digestion, but various research programs have replicated this experiment in animals, particularly cows. Cows have four stomachs, the biggest being the rumen, so some cows have surgery to make a fistula in the rumen, and a cannula is fitted over the hole. An article on research at the University of Illinois at Urbana-Champaign describes the operation.
Basically, a cannula looks like a ship porthole. A plasticlike cylinder is inserted in a cow, and the hole is plugged with a stopper in the same material. When a day's ration of cow chow hits the rumen - the first part of Bessie's four-part stomach - scientists like Professor George Fahey Jr. roll up their sleeves and dig in.
"We open the windows, remove some of the contents and study how efficiently the feed is being digested," Fahey says. From that sample, researchers determine how much food has been converted to energy and how much will move on through the bovine body as moo poo.
But why? What's the point of being elbow deep in chewed-up moo goo? "Today's dairy cow produces 90 to 100 pounds of milk each day," Fahey says. "Twenty-five years ago, they produced only 30 to 35 pounds a day." Studying what Bessie eats and how she processes it makes economic sense.
Having a hole in the rumen doesn't seem to bother the cows at all. An article about Ohio State University's program explains how cannulas may actually be good for a cow.
The digestion of food for nutrients in the rumen is done by millions of microorganisms. The abundance of microbes also keeps the cannulated cow healthy, often the healthiest in the herd, Weaver said.
"You would think that by having an opening in their sides would allow outside microbes to enter and infect the cows, but with there being such a numerous presence of natural microbes already in the rumen, the new microbes cannot compete for nutrients to survive," Weaver said.
Because these cows are so healthy, some farmers keep a cannulated cow on the farm to help improve the health of the other animals in the herd.
"Basically, the cannulated cows serve as a rumen fluid donor to sick animals. This is done by extracting rumen fluid contents from the cannulated cow and feeding it to the sick cow," Eastridge said. "The microorganisms in the fluid multiply and take the place of the bad organisms in the sick cow and make the cow healthy again."
In addition, cannulated beef cows live longer because they are more valuable than their compatriots destined to be eaten. Cannulated cows can now be found in quite a few places across the globe. See a recent video report on these cows. Link
(Image credit: Terry Whitt)