US meat, dairy and poultry producers on Thursday urged regulators to re-examine ethanol mandates, which are tightening limited grain supplies and forcing a run-up in feedstock prices that threatens their livelihoods.

“We are facing tighter and tighter supplies of grain that threaten to devastate meat, dairy and poultry producers and cause food price increases for the American consumer,’’ said Thomas Elam, president of FarmEcon, an agricultural and food industry consulting firm. “The government must not allow this to happen.’’