McDonald’s Inc. Board of Directors wants its shareholders to vote against a proposal by the Humane Society of the United States (HSUS) that would require the company buy 5% of its eggs from non-confined hens. The company cited insufficient scientific evidence to support the request.

McDonald’s Inc. joined the Coalition for Sustainable Egg Supply which is conducting a commercial-scale study on egg production. Researchers at Michigan State University and the University of California, Davis will evaluate conventional cages, enriched cages, aviaries and other floor systems.

Some fast food restaurant chains including Burger King, Subway and Wendy’s have sourced a small amount of eggs from non-confined hens.