That's one question researchers are asking in the emerging academic field called "animal well-being."

These researchers videotape chickens at play or rig doors so pigs can use their snouts to choose between eating their food alone or hanging out with other swine. The scientists attend conferences to hear papers with titles like "Hyperaggressiveness in Male Broiler Breeder Fowl."

Through behavioral research and animal biology, the experts try to find out: Are cows ever happy? Do pigs feel pain? What do chickens really want?

They know they're asking touchy-feely questions of a system that profits from mass slaughter. But they consider themselves pioneers.

"Asking scientific questions about an animal's feelings is brand new," says Edmond A. Pajor, an associate professor of animal behavior at Purdue University.

These Dr. Doolittles are financed in part by restaurant chains like McDonald's and KFC, which have been accused of helping to create harsh conditions on animal farms, where chickens, pigs and cattle are bred en masse. Of more than eight billion farm animals processed in the United States, most are crammed into cages, stalls and indoor barns before being killed. Their food is carefully rationed to promote optimal growth.

In recent years, especially in Western Europe, companies have felt rising pressure to treat animals humanely. Some food retailers have introduced labels indicating that an animal was raised with care.

Yet that's still far from ensuring that the animals are happy — a state that is hard to define for human beings but that scientists are nonetheless trying to attain for livestock.

"It's hard to talk about happiness, so we're trying to reduce the number of negative emotional experiences," Professor Pajor said. For now, researchers are seeking to eliminate pain, suffering and frustration.

Of course, if it were up to the animals, they might simply prefer longer lives. Dairy cows that used to be milked for five to seven years are now milked for two or three years before being made into hamburger. Chickens live an average of 46 days, birth to McNugget.

Then again, if the animals' lives are destined to be short, perhaps it's all the more important that they be sweet.