A national animal-rights group is mounting a scathing statewide ad campaign taking Wendy's International to task for the eggs the company buys.

One ad declares: "What's Wendy's attitude toward animal welfare? Frosty."

Through the radio and newspaper ads, the Humane Society of the United States is urging Wendy's to increase its purchase of eggs laid by hens housed in barns, not cages, and cut its purchase of eggs laid by caged hens.

Wendy's says it is focusing animal-welfare efforts on pork and chicken, areas where it can make the most difference, rather than eggs, because it buys relatively few. "We're not in a position to impact the issue," said Bob Bertini, a Wendy's spokesman.

The Humane Society of the United States notes, however, that Wendy's rival Burger King said it will phase in a cage-free policy, and by the end of the year the eggs would account for 5 percent of its total. Burger King is a major fast-food breakfast provider; Wendy's is just beginning to reintroduce breakfast.

The group's effort to shame Wendy's into making changes is an example of "activism" marketing, said H. Rao Unnava, a marketing professor at Ohio State University's Fisher College of Business.

Consumers are generally more receptive to such messages because more people have fears and opinions about the environment and the food chain, he said.