U.S. meat markets had so far been shielded from the effects of a deadly pig disease wiping out Asian herds. That’s starting to change.

As pork supplies plummet in China, the world’s top consumer is desperate for meat and is ramping up imports. As a result, it’s becoming harder to set longer-term protein contracts amid concerns over market volatility and changing trade flows, according to Jayson Penn, chief executive officer of Pilgrim’s Pride Corp., the No. 2 U.S. chicken producer.

“The contracting season is moving somewhat slower this year” for chicken, Penn said on a conference call with analysts following the release of third-quarter earnings. While major fast food restaurant chains are looking for beef contracts, “there are not many sellers willing to forward price,” he said.