The US cattle industry has got a major beef with Mayor de Blasio.

Hizzoner has vowed to cut the purchase of red meat for public schools, prisons and hospitals by 50 percent as part of his climate-change plan.

“We think that the mayor’s attempt, while maybe having the best intentions, is pretty misguided to single out beef as something that can have a significant impact,” Jennifer Houston, the president of the National Cattlemen’s Beef Association, told CNBC.

The mayor launched his war on red meat last month, announcing that 1,800 public schools would switch to “Meatless Mondays” by serving vegetarian meals at the start of the week.

“Cheer if you like hummus!” the mayor, whose two children are vegetarians, said at a March 11 press conference.

But Texas rancher Zachary Yanta told CNBC, “The mayor has missed the point on the purpose of these lunches, and that’s a nutritious meal for the people.”

“Of course, meat is still very good for you and nutrient-dense — and that means that only a small amount is needed to provide the recommended daily allowance,” Yanta said.

The mayor’s plan said beef “has a relatively high environmental footprint.”