Dairy plays a marquee role in Minnesota's fair season, from butter sculptures of dairy princesses to prize-winning Holsteins.

But with bird flu, or H5N1, spreading in herds across the country, thousands of cows must now test negative for the virus before showing up to exhibitions.

On Thursday, the Minnesota Board of Animal Health released new protocols for handlers of lactating dairy cows hoping to show animals at fairs. Cows will need to present a negative test for bird flu and a certificate documenting a veterinarian's inspection within a week before arriving at the fair. If an animal tests positive, the producer will need to quarantine the cows for a month.

The rules come on the heels of the first case of bird flu jumping into a dairy herd in Minnesota. Last week, the board reported a Benton County herd was sick with the same virus strain that has led to the mass culling of millions of birds in commercial flocks over the past two years.

For those who oversee fairs, the rules from the board were expected.

"We got the announcement less than 24 hours ago, and we're trying to figure out how to wrap our heads around what's going to have to happen," said Tom Peterson, who runs the dairy exhibitions in the heart of central Minnesota's dairy belt at the Stearns County Fair. "The onus is really on the exhibitor as far as the testing."

The introduction of bird flu not only poses a danger to humans, who can become sick, but also to dairy herds, which can lose milk production while they endure the illness. Eventually, cows recover from the virus. Still, it is deadly and fast-spreading in poultry. So state officials are sending notice across the agriculture community, including to 4-H participants, about safety precautions.

"Regardless of what species you show, you need to think about how you keep yourself, your family and your animals safe," said Sharon Davis, who leads animal science programs for 4-H at the University of Minnesota Extension.

Davis said there are just shy of 10,000 dairy animals participating in 4-H exhibitions this summer, with 1,276 youth participating.