Government officials and cattlemen are arguing over who is responsible for cleaning manure out of trucks returning to the United States after carrying cattle into Mexico.

The debate has caused a roadblock for Texas cattlemen and customs brokers who want to take advantage of newly allowed exports of U.S. cattle to Mexico.

The Agriculture Department has required trucks returning from Mexico, even after only a few hours, to be cleaned to avoid introducing cattle fever ticks or other parasites and diseases into the United States.

"This is American manure on these trucks. Why, when we finally have a chance to sell cattle to Mexico, are they putting up fences?" asked Pete Araujo, owner of the ABACO customs house, in the El Paso Times.

Texas cattleman John Hudgens said he had to delay 17 trucks of cattle in holding pens last week because of the restriction. He later arranged to have five trucks cleaned in Juarez, Mexico, but said it took two days because of weak water pressure.

Araujo said trucks carrying Mexican cattle into the United States are sealed after unloading, and he wants a similar procedure for U.S. cattle exports to Mexico.

U.S. cattle exports to Mexico have increased recently because of Mexico's decision to increase imports to relieve meat shortages and help stabilize meat prices.