COLLEGE PARK -- The topic today in Animal Sciences 101 is "Anatomy and Physiology of Digestion."
Nineteen students at the University of Maryland shuffle into the laboratory for a session on stomachs. But pens and notebooks won't do for this lab. The students shortly will slide a long plastic glove onto their right arm, take a deep breath and reach into a living cow's stomach -- and reach some more and wiggle and ram until they're shoulder-deep into the hot, massive paunch of the calm, massive cow.
"It's one of the labs the students tend to remember," deadpans the professor, Dr. Jerry DeBarthe.
In previous labs the students, many of whom want to become veterinarians, handled a chicken, stroked a sheep, corralled pigs, and harnessed a cow and led it around a pen. In this lab, Edward Morris, a junior from Columbia, thrusts his arm in, gets a whiff of stomach gas and utters: "Holy cow."
These are rumen-fistulated cows -- rumen, meaning stomach, and fistula, meaning an opening into the stomach. They can be referred to as cows with windows in their sides.
"They are windows as far as what they allow us to do," says Tom Moreland, manager of the university's research farm in Howard County, where the cows normally reside. "They allow us access to all four compartments of the stomach without any stress on the cow."
By analyzing samples from the rumen, the largest of the four compartments, researchers have determined what foodstuffs provide the most protein. They adjust cows' diets accordingly to produce more milk.
Rumen-fistulated cows became commonplace among research herds at colleges and universities in the 1950s. The procedure to insert the removable plug to close the "window" is considered minor surgery, Mr. Moreland says.
The cow suffers no ill effects, he says. In fact, he adds, it's more humane than what researchers used to do to collect samples: Block the animal's mouth open and force an inch-round plastic tube down its throat and into its stomach.
"No animal's going to like that," Mr. Moreland says.
The two Holsteins at College Park munch alfalfa hay in their stalls in the small barn on campus. Across the street in the Animal Sciences building, Dr. DeBarthe concludes an hourlong lecture on digestion.
Now it's time for some "firsthand" experience, he says.
"Some things about this may be a little put-offish to you," he says. "About the time you're reaching in and the cow contracts, forcing gas out across your face, that's the time to hold your breath."
The students eye one another warily.
The students crowd behind the cows. Dr. DeBarthe removes the four-inch plug from Cow No. 509 and then from Cow No. 483. They don't have names. One is 8 years old, and the other is 9. They've had windows in their sides since they were 3.
This must be one of life's stranger moments: Peering into the stomach of a cow . . . peering through a round window at what looks like a jumbo washer in slow motion, churning a load of cooked spinach.
But watch out. Here comes that gas. . . .
Kenya Howze, 22, a Washington resident who wants to be a zoo veterinarian, goes first. She slips on the long plastic glove and plunges in.
"It's pretty, uh, unusual," she says in a description oft-repeated.
She strains getting her hand through the densely packed hay the cow has been swallowing, regurgitating and chewing all day. She explores the bottom of the rumen, along the outside, down toward the front. She has long arms, but still can't reach into the reticulum, the front compartment. That's how large a cow's stomach is.
All 19 students explore. They're quite mature about it. And so are the cows. They stand there patiently, chewing their cud.
"I've never even like touched a cow before," says Kathie Moran, a 20-year-old junior from Bowie. "And now I can say I've had my hand inside a cow's stomach."
Lynn Sylvester, 28, a pre-vet student who grew up on a farm in Wisconsin, used to help the visiting veterinarian all the time.
"But I never did anything like this," she says.
Mr. Morris, of "holy cow" fame, says he's not sure he wants to tell anyone he stuck his arm into a cow.
"I think I'd best keep this to myself," he says.
The students peel off their filthy gloves and drop them into a garbage can. As they drift back to class with digestion out of the way, you can't help but wonder if they're the least bit worried about what's in store for them the week of Nov. 7.
The topic then in Animal Sciences 101 is "Anatomy and Physiology of Reproduction."