Taco Bell says it will crack nothing but cage-free eggs at its 6,000 U.S. locations by 2017.

The fast food chain said the announcement comes after "several years of planning."

Changing up supply chains to offer ingredients customers consider healthier and more sustainable is a popular trend in the fast food industry.

Taco Bell and Pizza Hut, both of which are Yum Brands (YUM) chains, have also committed to removing artificial ingredients. Taco Bell said Monday it plans to finish that switch by the beginning of 2016.

"Ingredient transparency is more important than ever to the next generation of Taco Bell customers," Taco Bell executive Liz Matthews said.

In September, McDonald's (MCD) said it will switch to cage-free eggs at its 16,000 U.S. and Canadian restaurants over 10 years.

And Burger King, owned by Restaurant Brands International (QSR), committed in 2012 to switching its egg supply within five years.

Food companies, including Kellogg (K) and General Mills (GIS), have also promised to convert to using only eggs from hens with access to open spaces.

There is no formal definition of cage-free. Some products with that label may come from hens that have very limited access to the outdoors or live in overcrowded spaces.

But animal-rights activists have celebrated the announcements because uncaged chickens can still "engage in natural behaviors."

Taco Bell's decision "will quickly improve the lives of countless animals and further cement the future of egg production as being one without cages," Josh Balk, the Humane Society's director of food policy, said Monday.