He is simply called Earl.

He has been a part of the animal science department of Iowa State for 11 years. He has entertained visitors and helped animal science students learn about the digestive system of cattle.

Earl is one of six fistulated steers on the ISU campus on which animal science graduate students conduct experiments and digestive tests. A fistulated steer is a cow that has had an operation cutting a hole into the side of the cow’s first stomach compartment, the rumen, and is protected with a removable rubber stopper.

“There is a lot of things we can do with fistulated steers,” said Jim Russell, professor of animal science. “They are a nice thing to have around for tours with kids. But the fact of the matter is that we are using them all of time.”

The animal science department uses these cows to analyze how steers and heifers digest silage, hay and other grains. In one treatment, the researchers give Earl different types of grasses and then collect samples from his stomach, Russell said. These test tubes are then left to ferment for 48 hours for further testing.

“Through this process I can get 250 samples at a time,” Russell said. “With a normal digestive trial it would take two weeks to run one sample.”

Another experiment typically done to fistulated steers is when the researchers put feed samples into the stomach and then take them out at different intervals, examining the extent of the digestion process, Russell said.

“The reason we have these animals is because it allows us to go directly into the animal’s stomach,” he said.

Allen Trenkle, distinguished professor of animal science, said researchers are most interested in the bacteria that break down the animal’s feed in the rumen. They want to know about materials digested in the cow’s stomach.

“We want to have the most efficient use of the feed they consume,” Trenkle said. “The opening on the side allows us to study their nutritional needs and measure the amounts of bacteria in the rumen.”

Once a cow has the operation done around the age of one year old, it can be used for experiments for years.

“Earl should be around for another 10 years,” Russell said. “The surgeries look good. There is no leaking at all. I would say Earl will have a long career here.”

The cows are primarily cared for by graduate students and undergraduates who work in the animal science laboratories. Graduate students name the cows in addition to feeling the insides of their stomachs.

“Earl is the long-timer of them,” Russell said. “There are a couple others. There was Big Bob. One was named Spike. Ask my graduate students. They become intimately acquainted with them.”

The process of looking at a cow’s stomach is not new. The first fistulated steer was at Ohio State University, Trenkle said.

When a former Ohio State professor came to Iowa State in the 1950s, he started doing the procedure here, Trenkle said. Since then, fistulated steers have become an attraction for visitors to the animal science department.

“People always call it the steer with the window in its side,” Trenkle said.

Russell said the only time he could remember a surprise reaction was when a student organization showed the cow to a group of elementary children. One of the children donated a $10 bill that the student put into a gel capsule and fed it to the cow. The students had planned to pull the pill out of the stomach.

“But the pill didn’t pass the cow’s teeth and it ate the kid’s $10 bill,” Russell said.

Both Russell and Trenkle said they can’t remember anyone having a negative reaction to Earl or any of the other fistulated steers.

“People realize that it is something novel,” Russell said. “But it is demonstrated to point out that it is a scientific tool. This isn’t something that we have done for no reason.”