About 1,000 people spilled into Riga's Dome Square on Friday for splashes of unpasteurized milk as farmers rallied against the EU's decision to raise milk quotas.
The protest came as milk supplies tightened in Germany on the fourth day of a boycott by dairy farmers, who are dumping milk rather than sell it for prices they say are too low.
Latvian farmers fear that the nation's dairy industry, which employs 60,000 people, will follow the sugar industry that collapsed after the Baltic nation of 2.3 million joined the EU in 2004.
Protesting farmers demanded equal subsidies for all EU farmers and demanded that Agriculture Minister Martins Roze quit.
"They don't know in Europe where we are, and who else should care about it other than our government?" farmer Anita Bordovska told Deutsche Presse-Agentur dpa.
A caricature in the Diena daily on Friday depicted Roze as a doctor who tells a sick cow lying in bed, "The EU doctors' council decided to amputate your udder, so you'd feel better."
Latvian farmers said they'd rather give their milk for free than at bargain prices
Since the EU has decided to scrap all milk quotas in 2015, it proposes raising the quotas every year until 2014 in an effort to provide a "soft landing" for milk farmers.
As a way to prevent dairy farmers' unrest, Latvia and Lithuania asked the European Commission -- the executive arm of the 27-nation bloc -- two weeks ago to subsidise milk exports to Russia to keep farmers in business.
The EC said that would not be the right move.
Writing on his blog before the protest, Roze said he supports the demonstration. Later, he added he wouldn't resign because that "would be running away from responsibility."
Government officials complained that the Baltic nation receives the least EU farm subsidies -- even less than EU newcomers Romania and Bulgaria.
Farmers agree with the complaint, but blame the Latvian government for providing outdated data on farms and farmland.
The protest organizers -- the Latvian Dairy Farmers Union -- warned that more protests may follow.
In the 1990s, Latvians stood in long lines outside grocery stores for a loaf of bread as the small Baltic nation struggled for its independence from the Soviet Union.