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Davis, California

Monday, June 24, 2024

Column: When Bessie thinks she’s pregnant

Here’s something I never knew: It takes 500 gallons of blood to produce one gallon of milk. Milk is 90 percent water, and that water comes straight out of the bloodstream. An animal’s mammary glands have to filter 500 gallons of blood to pull out the water and nutrients needed for milk. Your mom did this if she breastfed you. Cows do it, too – that vanilla ice cream is the stuff of blood.

At this point I’m thinking, “yuck.” But there’s a group of students at UC Davis that thinks lactation is worth a closer look. They want to see if they can trick heifers – female cows that have never been pregnant – into producing milk.

And if this quest means spending freezing mornings in a barn that smells like animal pee, so be it.

I spent my Sunday morning with a crew of animal science students at the UC Davis Dairy Facility. It was a damp, miserable day, and I shivered as I scribbled down notes. Meanwhile, student volunteers happily power-washed stalls and painted wooden walls white.

“Lactation and painting – how can you beat this?” said Marion Fischer, a senior animal biology major.

Their leader is Russ Hovey, an associate professor of animal science. Hovey is a lanky guy with a twangy Australian accent. He keeps a bedazzled cowboy hat in the barn, a souvenir from a past Picnic Day.

“They make me dress up in ridiculous outfits,” Hovey said, blaming students for the get-up.

I was becoming an animal science fan.

“Anyone want to see if the radio works?” asked Hovey, holding up a dusty boombox.

It didn’t work. From across the facility, I could hear a donkey bray.

Hovey explained to me how the research project will work: pregnant mammals produce high levels of a hormone called progesterone. The heifers in this experiment will receive shots of progesterone for seven to 10 days. This surge of hormones will trick the heifers into thinking they’re pregnant. Then the needle-stuck heifers will get a week off.

The next step is what interests me. Progesterone levels naturally drop when a cow gives birth. In fact, a drop in progesterone levels might actually be the cue for labor. When Hovey’s students stop giving the cows hormone shots, the cows’ bodies will switch to lactation. Gotta provide for the baby cow, they’ll think.

“We’re basically going to be doing an experiment that’s never been done before,” Hovey said.

This experiment is more than just a teaching tool. While students learn about the lactation process, Hovey will study udder development in these virgin cows. In his lab, Hovey’s research focuses partly on breast cancer so building up knowledge of mammary gland development is essential.

The heifers didn’t arrive in Davis until today, Jan. 19, so last Sunday was strictly about preparation. I stopped in a muddy stall to talk with Manuel Sandoval, a senior animal science major. He’s worked with cows before, he said. He once had a job where he had to track cows’ body temperatures.

“How do you take a cow’s temperature?” I asked, feeling dumb.

“In the rectum,” Sandoval replied.

I asked Sandoval if there are other animals he’d rather work with. After all that temperature-taking he must be sick of cows.

“No,” he said, laughing.

No one can say animal science isn’t a hardcore major.

Standing in the barn, I felt excited for the heifers’ arrival. My animal-science major roommate told me that other herds of cows on campus will have babies by April. I might as well go pay my respects.

After all, I do enjoy milkshakes.

MADELINE McCURRY-SCHMIDT’s previous dairy experience consisted of a summer working at a Dairy Queen. Oreo Cookie Blizzard, anyone? E-mail Madeline with column ideas at science@theaggie.org.


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