Like most pork producers, Smithfield has been caught in a tug of war with consumers.

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Poultry, beef and pork producers, facing rising feed bills, have called for the mandate to be waived.

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The system is voluntary, but 84% of the U.S.'s pork producers have gotten certified under the program, representing 75% of the U.S. pig inventory, according to the pork board.

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Smithfield and other pork producers in the U.S. follow a set of guidelines developed by the National Pork Board, an industry group, called the "Pork Quality Assurance Plus" program that governs the feeding and care of pigs.

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As a result, pork prices received by Mexican producers dropped 56 percent.

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Rising commodity prices can translate into higher food costs, especially as producers of beef, pork and chicken look to pass on higher animal-feed costs.

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