Two more companies – Marriott International and General Mills – have committed to supply chain changes, including elimination of gestation crates for breeding sows.

General Mills' announcement was publicized Tuesday. A statement posted on its website says General Mills supports the development of pregnant sow housing alternatives to gestation crates.

The company says it understands that the development and implementation of alternative systems may be a long-term process "that could take up to 10 years."

Companies map plans for crate-free pork, cage-free eggs.

General Mills, says it will favor pork suppliers that provide actionable plans by 2017 to "create traceability and end their use of gestation crates within the U.S. pork supply chain."

The company is the manufacturer of many recognized brands, including Haagen-Dazs, Yoplait, Cheerios, Pillsbury, Betty Crocker and Green Giant.

General Mills in a statement says it will also support cage-free egg production. "To encourage the development of alternative production methods in the U.S., General Mills purchased one million eggs from cage-free hens for our U.S. retail operations in 2012," the statement announces.

The Minneapolis, Minn., based company also sources milk from cows not treated with rBST.

Marriott International, based in Bethesda, Md., also committed to new policies on pork and eggs, announcing Tuesday that it would shift to gestation crate-free supplies by 2018 and cage-free eggs by 2015.

The policies are supplementary to the 2011 transition to cage-free eggs at JW Marriott locations.

"Marriott International cares deeply about animal welfare and environmental sustainability, which is why we're so committed to seeing an end to gestation crates for pigs and battery cages for hens," said Brad Nelson, vice president of culinary and corporate chef for Marriott International in a statement to the Humane Society of the United States.

The announcement is "the right thing for animals, the environment, our customers and our company," he said.

The two companies join McDonald's, Kroger, Hillshire Brands and others in plans to eliminate gestation crates from their supply chains.