McDonald’s is finding Americans have a hearty appetite for fresh beef.

On Monday, the fast-food giant announced that in the year since it swapped frozen for fresh beef in its Quarter Pounder, sales of the iconic burger are up 30% on average.

“Our customers are loving it,” Marion Gross, McDonald’s senior vice president of supply chain management, said in an interview with USA TODAY. “We sold 40 million more Quarter Pounder burgers nationally in the first quarter of this year compared to the quarter in 2018.”

Gross said the burgers are hotter and juicer than frozen beef. Wendy’s, Culver’s, Five Guys, Whataburger, Shake Shack, In-N-Out Burger and Smashburger also promote using fresh, not frozen, beef.

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“Our customers tell us they have an interest in understanding where it comes from, what goes into it and how is it prepared,” Gross said. “We’re trying to be more transparent and make some necessary changes to delight our customers as we embark on our journey to be a better McDonald’s.”

Gross said the transition to fresh beef was the most significant change at U.S. restaurants since All Day Breakfast was rolled out in 2015. Fresh beef is not available in McDonald’s restaurants in Alaska, Hawaii and U.S. Territories.

In April, McDonald’s announced it was moving away from its premium line of Signature Crafted Recipes as it added more options to its Quarter Pounders lineup.

According to Robert Derrington, senior restaurant analyst at the Telsey Advisory Group, a brokerage firm in New York, Signature Crafted Recipes foods weren't selling well, plus McDonald's upped its game by introducing non-frozen meat in the Quarter Pounders.

"They've had success with fresh beef," he said in April. "It appears they don’t need to supplement the higher end of their menu. Instead, they can do that successfully with their core products with updated ingredients."

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While McDonald’s is finding growth with fresh beef, competitors are seeing success with plant-based and meat alternatives. Burger King plans to take its Impossible Whopper, developed by Silicon Valley-based Impossible Foods, nationwide this year.

Gross called it a “hot topic,” one that McDonald’s is watching.

“We’re committed to offering a variety of menu choices for our customers and, importantly, we’re going to listen to what our customers want from us,” Gross said. “We’re trying to understand what some of these changing trends are and these evolving tastes and if our customers want those type of products from us then we’re going to figure out how to deliver.”

McDonald’s released the Big Vegan TS in its Germany restaurants in late April.

“But, at this point in time, we don’t have anything planned in the U.S. beyond what we’re doing in Germany,” Gross said.

Follow USA TODAY reporter Kelly Tyko on Twitter: @KellyTyko