LOS ANGELES — The California Milk Advisory Board continues its "Happy Cows" advertising campaign, but there are few happy dairy farmers right now.

Frustrated with low milk prices, dairy farmers are selling cows for hamburger meat and threatening to dump milk into sewers. Many are burning through their life savings hoping to survive the slump, and others are exiting the business.

Two farmers have killed themselves.

The pain is being felt throughout the U.S. industry, but it's especially keen in California, the No. 1 dairy state. The Golden State's 1,800 dairies produce $7 billion worth of milk annually, more than one-fifth of the nation's supply. Slumping international demand combined with an American public ordering fewer cheese pizzas has turned the milk market sour.

Current prices are about half of what it costs California producers to feed and milk their herds; every carton sold in the supermarket represents a loss on the farm. Farmers are staying afloat by getting loans secured by every cow, tractor and acre they own. But experts say that if milk prices don't rise in the coming months, many farmers will burn through their cash and go out of business.

"This is an unbelievable career wreck. The amount of wealth being destroyed in this industry every week is just mind-boggling," said Geoffrey Vanden Heuvel, who owns dairies in Chino and Corona.

Two California dairy farmers killed themselves in the past six months out of despair over finances, according to associates.

"We are getting more phone calls and concerns about suicides than ever," said Michael Rosmann, executive director of AgriWellness Inc., a Harlan, Iowa, nonprofit operating mental-health hot lines for farmers in seven Midwestern states.

Through much of 2008, the average milk price hovered around $17 per 100 pounds — although consumers purchase milk by the gallon, the industry measures by pounds. The bottom fell out of the market when the economy tanked last fall. Prices now hover around $10, according to the California Department of Food and Agriculture. Farmers generally need at least $16, and often more, per 100 pounds to break even, depending on their debt, feed requirements and other factors.

Tom Marchy remembers learning how to milk cows from his grandfather on the family's spread in Stanislaus County. Now 48, he saw disaster looming in the industry last fall and called it quits.

His biggest customer had just canceled his milk contract, and "it was hard to find anyone else to ship to so I just got out."

Collectively, U.S. farmers need to slash milk production by about 5 percent to bring supplies in balance with current demand, "but we have no good mechanism to do that," Vanden Heuvel said.

Farmers have faced low prices before, but what's different this time around is that their cost for feed and other expenses is high compared with what the milk sells for, said Bill Schiek, an economist with the Dairy Institute of California in Sacramento.

"They are just bleeding cash," Schiek said.