The cardinal rule in dairy judging is that, if you’re in doubt, you pick the cow with the best udder. Few people know that better than Brian Coyne, who grew up on a dairy farm near Eau Claire and began judging cows when he was 10. Yet in the biggest contest of his life, he was about to throw that maxim out the window.

Coyne, a CALS senior majoring in dairy science, was getting his first look at a group of Milking Shorthorns—four of the 48 cows he evaluated during the National Intercollegiate Dairy Judging Contest at the 2010 World Dairy Expo—and the first one in line really caught his eye. He liked every part of her, save one: She clearly had the worst udder of the group.

“She was huge,” Coyne recalled later. “She was really clean-cut. She had a big, sharp front end on her.” Despite her mammary shortcomings, she had what Coyne looks for in a great cow: “She was really dairy.”

Dairy” is a compliment paid often around venues like the World Dairy Expo. You hear it from judges at the event’s seven major breed shows, from onlookers at the big-money cattle sales held each night, and from the visitors who stream through the barns that house nearly 2,500 of the world’s best show cows. The term is a bit of industry shorthand, usually uttered in awestruck tones to explain what separates an outstanding cow from one that’s merely good: “She is just so dairy!”

To be successful in the milk production business, you have to be able to recognize a good cow. Dairy judging contests teach one of the oldest ways of doing that: giving her a good long look, from muzzle to hip bones and rump to hooves, to see how closely she conforms to “true type,” the hypothetical perfect cow. In the most practical sense, being dairy means that a cow has a body that promises great things in the milking parlor.

“We’re talking about openness to rib, a sweeping slant to ribs, overall angularity and length of neck,” explains CALS dairy science instructor Ted Halbach, who coaches the students on the UW-Madison dairy judging team. “It means she looks like she’s giving a lot of milk.” These are traits Halbach knows well. In his dozen years as coach, the UW judging team has won three national championships, including one in 2010. He won the contest himself as part of Wisconsin’s 1980 team, and he’s the son of a winner. His father competed and won as a UW senior in 1939.

But a lot has changed in the 90 years since the national judging contest began. These days, farmers use more than their eyes to tell them about a cow’s milk-making potential. They rely on extensive data about her pedigree and the performance of her mother and aunts and sisters. And now the sequencing of the cow genome—completed in 2009 by a team of 300 scientists from 25 countries—has opened a vault of new data and new possibilities.