NEW YORK (AP) — Dunkin' Donuts says it will start using cage-free eggs in its breakfast sandwiches and eliminate "gestation crates" from its pork supply chain.

The Canton, Mass.-based company said Wednesday that it will transition 5 percent of its eggs to cage-free by the end of next year; it did not set a timeline for completing the switch.

To determine a timeline for eliminating gestation crates, or breeding cages for pigs, the company said it will start by requiring its U.S. pork suppliers to outline their plans to achieve that goal.

Josh Balk, director of corporate policy at the Humane Society of the United States, said that's the first step for most companies that want to stop the use of gestation crates.

"There's been a massive trend by the largest pork buyers to demand their suppliers eliminate gestation crates," he noted.

Other major fast-food chains that have committed to eliminating use of pig crates include McDonald's Corp., Burger King Worldwide Inc., Wendy's and Subway, as well as several supermarket chains such as Kroger Co. and Safeway Inc.

Gestation crates often confine mother pigs for their entire lives, or about four years, Balk said. The space is usually so small that pigs can barely move.

"For as long as students go to high school, these pigs can't even turn around," he said.

Several companies have also said they will start using cage-free eggs, although the commitment levels vary.

Egg and pork producers have argued that easing confinement standards for animals raises production costs, making their businesses less competitive.

Shares of Dunkin' Brands Group Inc., the parent company of Dunkin' Donuts, fell 48 cents to $28.97 in morning trading.

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  • Dunkin' Donuts

    In September, Dunkin' Donuts announced that it plans to <a href="http://www.huffingtonpost.com/2012/09/26/dunkin-donuts-cage-free-eggs-gestation_n_1916260.html?1348678200" target="_hplink">eliminate all gestation crates</a>, but has not set a timeline. It is also moving toward cage-free eggs.

  • McDonald's

    At the end of May, the country's leading hamburger chain by sales announced a plan to eliminate its suppliers' use of gestation crates by 2022.

  • Denny's

    On May 15, Denny's announced it would work with its suppliers to end the use of gestation crates for its pork products.

  • Safeway

    In May, Safeway -- the country's second-largest grocery chain -- said it plans to <a href="http://www.huffingtonpost.com/huff-wires/20120507/us-safeway-humane-pork/" target="_hplink">stop buying meat</a> from suppliers that use gestation crates.

  • Burger King

    On April 23, Burger King pledged to <a href="http://www.huffingtonpost.com/2012/04/25/burger-king-gestation-crates_n_1451703.html" target="_hplink">eliminate the use of pork from pigs raised in crates by 2017</a>. The company also pledged to offer entirely cage-free eggs by 2017.

  • Wendy's

    In March, Wendy's announced it would work with its U.S. and Canadian pork suppliers to <a href="http://www.huffingtonpost.com/2012/03/23/wendys-animal-treatment_n_1375724.html" target="_hplink">phase out the use of gestation crates</a>.

  • Compass Group

    Also in March, Compass Group announced it would <a href="http://www.bizjournals.com/charlotte/blog/going_green/2012/03/compass-group-will-end-contracts-with.html" target="_hplink">phase out the use of meat from pigs raised in gestation crates</a> by 2017. Compass Group runs dining operations at about 10,000 companies, hospitals, senior living centers, schools, colleges and universities, making it the largest food service company in the world.

  • McDonald's

    McDonald's also announced in February its <a href="http://www.huffingtonpost.com/2012/02/14/mcdonalds-gestation-crates_n_1275942.html" target="_hplink">plan to stop using meat from pig raised in the crates</a> by 2017.

  • Hormel, the maker of products like Spam, announced in February it <a href="http://www.huffingtonpost.com/2012/02/02/hormel-gestation-crates_n_1249707.html" target="_hplink">pledges to eliminate most gestation crates by 2017</a>.

  • Bon Appétit Management Company

    Also in February, Bon Appetit announced it would <a href="http://www.latimes.com/business/money/la-fi-mo-bon-appetit-gestation-crates-20120220,0,7675759.story" target="_hplink">stop buying pork from providers who use gestation cates</a>. Bon Appetit runs more than 400 cafes across 31 states.

  • Smithfield Foods

    Smithfield Foods, the world's largest pork producer, announced late last year it would <a href="http://www.huffingtonpost.com/2011/12/08/smithfield-gestation-crates_n_1136567.html" target="_hplink">end its practice of using gestation crates</a> for pregnant hogs by 2017.

  • Oscar Mayer

    In early July, Oscar Mayer pledged to source its pork from suppliers that <a href="http://www.huffingtonpost.com/2012/07/09/oscar-mayer-gestation-crates_n_1658670.html" target="_hplink">no longer use gestation crates</a>. Oscar Mayer is owned by Kraft Foods.

  • Sysco

    On July 23, Sysco <a href="http://www.huffingtonpost.com/2012/07/24/sysco-gestation-crates_n_1698971.html?1343152570" target="_hplink">pledged to work with its producers to stop the use of gestation crates</a>. Sysco is the world's largest broadline food distributor.