Milk farmers' groups said world prices had sunk so much they are having to sell milk at half their production costs, leaving more and more farmers unable to pay their bills.
To highlight their desperation, about 300 tractors dragged milk containers through plowed fields in southern Belgium, dumping a day's worth of milk production in that region.
"It is a scandal to dump this, but we have to realize what the situation is," said Belgian farm leader Erwin Schoepges. "We need a farm revolt."
The crisis has driven many EU farmers into a "milk strike," with thousands refusing to deliver milk to the industrial dairy conglomerates that produce anything from skimmed milk to processed cheese.
Romuald Schaber, the president of the European Milk Board farmers' group, said up to half the milk farmers in some areas were refusing to deliver their milk and predicted the first shortages could hit some supermarkets as early as next week.
"We are looking at a real catastrophe. Nobody can produce milk at these prices," he said.
To raise milk prices from the current 18 to 24 euro cents ($.26 to $.35) a kilo to the 40 cents ($.58) they say it required to cover costs, the farmers are demanding tougher EU production quotas. More government support is essential to stave off bankruptcies, they claim.
But the Europe-wide protests have also suffered from a lack of unity among farmers, with many either objecting to the spilling of milk or the strike itself.
The 27-nation EU already pays for extra help to farmers in addition to the euro55 billion ($80 billion) it pays annually for support payments, market regulation, storage aid, rural development and other projects.
Since the recovery from World War II, farming in Europe has always been exempt from free market forces as governments sought to end hunger and rationing by paying farmers to increase food output.
By the 1990s, Europe's farms were paid to produce too much and the scandal of wasteful EU butter mountains and wine lakes prompted talks on reforming the industry to phase out state support. Quotas for milk production are scheduled to end in 2015.
Agriculture is still one of the most shielded economic sectors in the EU, but it has not been able to protect farmers from the global financial crisis that caused demand to crash.
"If we go on for another three months like this, 40 percent of French milk producers will be condemned to bankruptcy," said Pascal Massol, a Breton farmer who leads the French protests.
EU farmers group Copa said without quick EU action, farmers would lose euro10 billion ($14 billion).
The European Union opposes tougher quotas, seeking instead to abolish the practice to let market forces have a stronger influence on production.
"I understand their emotions," EU Farm Commissioner Mariann Fischer Boel said of Wednesday's milk protest. "It is a human reaction."
