The proposal was advanced by the Humane Society of the United States.
Some major fast food companies, including Burger King, Subway and Wendy’s, and the retailers Wal-Mart and Trader Joe’s, have already made some level of commitment to purchasing or selling cage-free eggs.
But the McDonald’s board said on Friday that the science was not there to support a switch.
“As we have examined this issue over the years, we have determined that there is no agreement in the global scientific community about how to balance the advantages and disadvantages of laying hen housing systems,” it said in a proxy statement.
McDonald’s says that its egg suppliers can use “battery cages” that afford a minimum of 72 square inches of floor space per hen. The Humane Society counters that this is not enough space to allow a hen to fully spread its wings.
Last year McDonald’s joined the Coalition for Sustainable Egg Supply, which is organizing a commercial-scale study led by Michigan State University and the University of California, Davis, to examine different housing options for egg-laying hens.
The study will look at the pros and cons of producing eggs in a cage-free system, which is said to provide enough space for hens to walk and stretch their wings; an “enriched” environment in which hens have access to perches and nests; and battery cages, which house the vast majority of egg-laying hens in the United States.
McDonald’s and some other major food companies like Bob Evans Farms say the study will help them make more informed decisions on egg purchases.
But Paul Shapiro, senior director of the Humane Society’s factory farming campaign, argues that there is “already an abundance of scientific evidence” to support moving away from battery cages, including a Pew Commission report that concluded that they were inhumane.
Mr. Shapiro also pointed out that McDonald’s had committed itself to going 100 percent cage-free by the end of 2010 for all its European operations. (The European Union passed a law that bans conventional battery cages starting in 2012).
“There’s a big disparity between what McDonald’s is doing in Europe and in the United States,” he said.
A spokeswoman for McDonald’s, Lisa McComb, attributed the disparity to the high consumer demand for cage-free eggs in Europe and a more robust cage-free egg production infrastructure there.