Hole-y Cow!

In the spring of 2015, I took a science communication course that gave me the opportunity to explore and create a really fun final project. This piece talks about my adventure with a fistulated, or cannulated, steer.

Popular TV shows have highlighted it, our grandparents may talk about it, and I got to see it; a cow with a hole in its stomach.

Dr. Jim Russell, professor in animal science at Iowa State University, offered to take me to the Beef Nutrition Farm where the steers of interest are housed. He handed me a white lab coat, two rubber gloves, and one large plastic glove that fit up over my shoulder. I balanced the equipment with my own; a notebook, a pen and my camera, ready to be surprised.

Cattle are ruminant animals, meaning that they have a more complex stomach than humans with four total compartments. Overall, being a ruminant makes it easier to get energy from plant materials. Due to microbial and fermentation activity within the rumen compartment, cattle can gain weight on the plant material that humans eat to lose weight.

Technically speaking, these steers are fistulated, meaning they have a rubber grommet called a cannula and a plug in their side, just in front of their hip bone. These thick, rubber grommets are put in place to give scientists and students the chance to see the digestive system in a live animal and to aid in many kinds of research. With Russell, the research has to do primarily with digestibility of potential feed materials.

“Having the capability to get that rumen fluid helps us run samples,” Russell said, adding that with modern lab equipment, this fluid can assist in running up to 80 samples of feed at one time, which would take years to do otherwise.

Russell said the process of inserting a cannula is relatively simple. A local anesthetic is used so the animal won’t feel pain, an incision is cut, and essentially the wall of the rumen becomes healed to the animal’s skin. Then, the cannula is put in place, and the animal can live comfortably for their entire natural life.

“As long as you do it properly and get that good, tight seal, they can stick around forever and there are a number of uses for them,” Russell said. “It’s really quite amazing.”

How the stomach works and the microbes within it are entire fields of study, and they benefit greatly from having live animals to observe and study.

At Iowa State, there are four such animals. One of which I had the chance to meet.

The farm looked about how you would expect a small cattle farm to look; there was a long drive way, with wooden fences lining it. Towards the end of the lane, there were metal Morton buildings, machine sheds, and a small silo. In the pen nearest the road, there were four fully grown black steers, all fistulated. As we walked towards them, they walked up to the fence with inquisitive eyes, mooing and poking their big, wet noses towards my camera.

“They get to be pretty good old boys,” Russell commented.


Jim Dahlquist, the farm manager, helped us escort one of the “boys” to a chute so we could examine his fistula.

His ear tag said 351, but Dahlquist said the graduate students have other names for them. Dr. Stephanie Hansen, assistant professor in animal science at Iowa State, has also worked with these animals in her research, and recalled some of their names.

“Gary, Sheldon, Henry… I always forget the other one,” she said. “They’ll come up to the fence and lick your hand.”

351 was mostly motivated by thick patches of green grass, which halted his movement periodically on his saunter to the chute. As he got settled, I could get a closer look at the cannula. It was a thick, translucent and rubber with a hole big enough for a hand to fit inside. The plug in the center fit tightly into the cannula. The plug keeps the opening sealed for a majority of the time to minimize the impact of external factors on the rumen. Russell removed the plug, and steam wafted out of the opening; not unlike the steam that comes off of a football player when they take off their pads on a brisk fall evening.


As Russell removed some of the half-digested material, I was taken aback by how unremarkable it was. It didn’t seem the slightest bit unnatural. There was soggy, brownish golden bits of hay, grass and grain, stuck together with a brown liquid, some of which sloshed out of the opening when he moved. The mixture had a smell, but not necessarily a bad one. It smelled something like silage, a fermented plant material feedstuff, mixed with old gym shoes. Or maybe stinky feet and old dirty dishes.

After I observed the opening, I pulled on the long, plastic, over-the-shoulder glove. I fit my hand through the cannula and felt around inside. It was warm and soggy, but mostly it just felt big. Russell noted that in some studies, they empty the rumen and examine the contents. When they do that, it can fill a 30 gallon tub.

The cannula was situated in the upper part of the rumen, in what Russell called the gas bubble. This is where I initially reached my hand into. Just below the opening was the fiber mat; the soggy, half-fermented feed material layer. On the bottom of the rumen sat the liquid.

“Of course, they’re always being mixed,” Russell noted.

These layers can have a lot to do with research. For instance, Dr. Hansen recently studied sulfur toxicity and the harmful gases that can be created in the stomach of cattle based on different feed sources. It was found that distiller’s grains, a byproduct from ethanol production and a cheap feed source, can build up hydrogen sulfide in cattle’s stomachs, so when they eructate or burp, they breathe in this unfriendly gas.

This study played an important role for cattle producers, as it found that with adding different levels of forages to the cheap distiller’s grains, they can manage sulfur toxicity and not put their livestock in harm’s way.

“Obviously, we want to keep animals alive and safe,” Hansen said.

As a part of this study, the plug in the cannula was fit with a second, smaller cap that could fit a probe to measure gases. That way, taking gas samples didn’t require the whole cannula to be opened, just the smaller cap was removed to fit the probe. The study also used larger data collectors that sat in the bottom of the rumen and measured temperature and pH of the mixture.

Dr. Russell’s work with the fistulated steers worked a little differently. Though he’s been working with animals like these since 1972 while he was in graduate school at the University of Wisconsin, his research now is mostly focused on feed quality and digestibility. Using liquid samples from the animals, he can quickly test many feed materials in his lab.

351 didn’t seem to mind the attention. After he was let out of the yellow, metal chute, he was rewarded with some time to munch on the thick, green grass. The humans were rewarded with a growing knowledge of ruminant digestive systems, and, of course, the company of Gary, Sheldon, Henry and… the other one.

Beef Nutrition Farm



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