text: Mexican restaurant Chipotle has been leaving customers hungry for certain ingredients unsatisfied because not enough farms can meet its strict standards. The fast-casual chain, which plans on having 2,000 stores by the end of the year, removed carnitas pork burritos from roughly a third of its locations in January, but still doesn't have a stable supply of the meat. Chipotle, which dropped one of its pork vendors earlier this year, only uses humanely-raised pigs that have not received added hormones, though they have become harder to acquire after demand has risen. Fast-casual chain Chipotle says that it does not know when it will have enough pork to supply all of its stores with sustainably raised meat for its carnitas burritos (file photo) 'We don’t know for sure when we’ll be fully supplied again,' Chipotle spokesman Chris Arnold told Bloomberg. The restaurant's pigs also need access to the outdoors and living spaces with large supplies of straw for their meat to make it into Chipotle burritos, tacos and bowls. Other retailers such as grocery store chain Kroger have begun taking up some of Chipotle's ethical standards. McDonald's pledged to stop using chickens treated with antibiotics at its stores in the next two years. The grocer and Dunkin Donuts have both said they will stop using pork from farms with gestation crates, where sows are kept in two-foot wide containers and are repeatedly impregnated without being able to move. The carnitas pork shoulder meat at Chipotle (pictured in burrito) comes from pigs that are raised outside or in living spaces with large supplies of straw (file photo) However, fewer than five per cent of pigs in the US are raised in a way that meets Chipotle's standards, according to CBS. It has been rotating its small supply of pork, of which it uses only pork shoulder, to different stores so that each location can have carnitas at least sometimes. Farmers are wary of the increased production cost for premium, antibiotic-free pork and worry about finding people to pay an appropriate price for the 'premium' meat after Denver-based Chipotle has the bits it wants. Chipotle said that supply constraints were behind 6.3 per cent price increases last year. As of Thursday morning, its stock price had fallen more than five points since news of the continued shortage was published Wednesday. Chipotle says that constraints on receiving supplies that met their standards led to 6.3 per cent price increases last year (file photo) When sustainably raised beef runs out, the store uses conventionally raised cows, but it views the conditions of factory farmed pigs by the world's biggest pork producers as particularly bad. Beyond the farming side, regular US pork production was also criticized earlier this year by meat inspectors after several of the nation's slaughterhouses transferred to a new system that increases the numbers of hogs killed per minute to 1,300. Whistleblowers from the United States Department of Agriculture said that toenails, hair and fecal matter may be creeping into Americans' pork under the new regulations. Chipotle's most popular protein is chicken, with only seven per cent of entree orders calling for carnitas. The restaurant has also warned of possible guacamole shortages.
target: Mexican restaurant chain cut carnitas pork from third of stores this year .
  Company doesn't know when it will be fully supplied again .
  Dunkin Donuts, McDonald's switching to more sustainably raised meat .
  Farmers need buyers for 'premium' pig parts after Chipotle takes shoulders .