Washington State University scientists are developing thick hides under a barrage of jokes about research into the effect of methane from cattle belches on global warming.

Syndicated humorist Dave Barry featured the study in a recent column. A character on the television show "L.A. Law" cited the project as an example of wasteful government spending. Letter-writers have questioned the value of the studies when children are starving."You get pretty thick-skinned," researcher Hal Westberg said Friday.

"And a little tired of the time it takes to answer the questions," colleague Brian Lamb added.

The researchers received a $210,000 federal grant to monitor methane gas belched by cows, using backpack measuring devices strapped to the cud-chewing animals.

Methane, a colorless, odorless gas, helps traps heat in the atmosphere.

Cattle are believed to be the world's third-largest source of methane, behind wetlands and rice paddies.

Lamb said a cow belches about 200 liters of methane a day, making the world's 1.25 billion cattle responsible for about 15 percent of the Earth's methane.

"I think it's important people understand that climatic change is a serious threat," Lamb said. "Understanding the climatic change means we have to understand mundane things like sewage treatment plants and cow belching.

"We've got to attack this one piece at a time, and this is one piece."