OAK BROOK, Ill. — McDonald’s Corp., in looking to offer a more nutritional menu, have apple producers smiling these days – the world’s largest fast-food operation started offering sliced apples in September as part of every Happy Meal it sells in select restaurants in California and three other Western states.

Customer response has been favorable, and the chain will continue adding pre-packed sliced apples to the menu of all 14,000 U.S. stores by March 2012, said Ashlee Yingling, a McDonald’s corporate spokeswoman.

“This is a phased rollout. It started in September and all restaurants will have the new Happy Meal by March 2012. That said, it’s too soon to discuss specific types of apples and the sourcing,” Yingling said.

She declined to discuss specifics about who would supply the chain’s stores with sliced apples, or the volume of apples the company expects to need to include in all Happy Meals. But news of the move has apple producers, particularly in top-producing states such as Michigan and New York, excited.

“This is very big news for apple growers in the U.S.,” said Peter Gregg, communications director for the New York Apple Assoc.

Denise Donahue, executive director of the Michigan Apple Committee, said the move is big not only for producers, but for consumers, as well. “Kids just love apples. Sliced apples are especially appealing to kids,” she said.

The thinking among apple producers is McDonald’s will have to buy the fruit regionally, given the short shelf life of packaged sliced apples.

“Even if they don’t use local growers extensively, the bottom line is that anything that gets kids, and adults, to eat more apples, the healthier everyone will be,” said Sherry Mills, who helps run the 4,000-tree Mills Apple Farm in southeastern Illinois.

McDonald’s since 2004 has offered sliced apples as an alternative item, but this change will put sliced apples in every Happy Meal. In addition to a 1/4-cup of sliced apples, buyers of Happy Meals will still get fries, but about half the amount that are included now, Yingling said.

Consumers also may request an extra bag of apples to replace the fries.

“Recent research has shown that younger children are consuming more fruits and vegetables, but we still have a long way to go to increase consumption to meet daily recommendations for these important food groups,” said Elizabeth Pivonka, president and CEO of Produce for Better Health Foundation.

“McDonald’s announcement to include apples in every Happy Meal … further strengthens their seven years of support in our campaign to educate children and their parents on the benefits of fruits and vegetables.”

Another fast food chain, Arby’s, began offering sliced apples in its kids’ meals Oct. 3 in all of its 3,600 U.S. stores. The apples replace fries in Arby’s meals, although customers can request fries with kids’ meals instead of apples.

McDonald’s has done well during the U.S. recession and since, with third-quarter profit up by 9 percent to $1.51 billion. It is the company’s ninth straight quarter of gains.

One key statistic: McDonald’s revenue at stores open at least a year was up 5 percent compared to the previous quarter.