Top U.S. pork processors Smithfield, Tyson Foods Inc and Cargill Inc reverted back to pricing hogs based on U.S. Department of Agriculture data, industry sources said this week, after a 16-day government shutdown had caused the suspension of daily USDA reports.

Packers use the USDA's Agricultural Marketing Service (AMS) daily reports to determine the prices they pay hog producers. But the reports, along with thousands of others on which the U.S. agricultural industry depend, were unavailable during the government shutdown, forcing packers to use alternative pricing methods.

No. 1 pork packer Smithfield priced hogs using CME Group lean hog futures contracts during the shutdown.

Tyson and Cargill calculated hog prices using data from Urner Barry, a private U.S. analytical research firm closely followed by livestock packers and traders for its meat prices and data, until USDA-AMS price data was available.

Smithfield, Tyson and Cargill spokesmen were unavailable for comment.