Twenty-one Harvard donors have pledged to withhold further donations to the University until Harvard switches to providing exclusively cage-free eggs in its dining halls, according to Humane League Campaign Coordinator David Coman-Hidy.

A campaign organized by students and assisted by the Humane League contacted benefactors from three donor societies—the Harvard Yard Society, Harvard Medal Recipients, and the 1636 Society.

“As a financial supporter of the College, I would like to think that my money is going to support an administration that is both responsive to its students and responsible towards the environment and animals,” read the letter signed by the boycotters. “I look forward to hearing back from your office with news of a complete switch to cage-free eggs—until then, I will not be making any more donations.”

In 2007, HUHDS answered a student campaign with a partial switch to cage-free eggs. Currently, all shelled eggs that are cooked individually—including hard-boiled eggs and fried eggs made at the grill—come from cage-free farms. These account for about 20 percent of the eggs used in Harvard dining halls.

But other entrees, including scrambled eggs, are made with liquid eggs from farms that use battery-cage methods.

AnnaLise S. Hoopes, who started the original campaign in 2006 while she was a graduate student at Harvard, said that while the University “took a courageous step toward ending these practices,” she would like to see Harvard make the full commitment to cage-free.

“I think it is wrong to support an industry which inflicts abuse and suffering on thousands of voiceless animals,” Hoopes said.

In this year’s more recent campaign, 5,000 Harvard students and faculty signed a petition supporting the use of cage-free eggs, according to Marina N. Bolotnikova ’14, one of the students spearheading the movement.

Ted A. Mayer, assistant vice president for hospitality and dining services, responded to a student petition and letters in a blog post in April.

Mayer cited nutritional, safety, humanitarian, and economic reasons for continuing to purchase from battery-cage farms.

Mayer pointed out that cage-free farms do not guarantee humane treatment because even cage-free facilities have been shown to have problems, including space constraints, de-beaking, and bird-on-bird aggression.

“In my ideal world people wouldn’t eat eggs at all,” Bolotnikova said. “I think cage-free, though imperfect, is a really important first step in thinking about where our food comes from.”

Bolotnikova, also a Crimson editorial editor, said that she believes that the economic costs are HUHDS’s primary concern.

“They haven’t really been as open as I would have liked,” she said.

Mayer wrote that the costs of switching to cage-free would be about $100,000.

Many of Harvard’s peers have made the switch. Yale, Princeton, and the University of Pennsylvania are all exclusively cage-free.

—Staff writer Zoe A. Y. Weinberg can be reached at zoe.weinberg@college.harvard.edu.