US cattle ranchers filed a lawsuit in the Lincoln District Court on Friday, alleging that the meatpacking divisions of ConAgra Foods and Cargill have been purposefully depressing the cash cattle market.

If the case is accepted by the court, cattlemen who sell by taking bids from buyers on a weekly or daily basis would have to prove that the two companies use livestock contracts and ownership to depress the market, and that they have been violating the 1921 Packers and Stockyards Act by engaging in monopolistic practices.

Red Oak, Iowa-based rancher Gordon Reisinger, a plaintiff in the lawsuit, explained that because packers control the slaughter supply through their beef slaughtering plants, they can therefore bid less aggressively on remaining cattle.

Mark Klein, a spokesman for Cargill's Excel division, insisted that "study after government study over more than a decade has shown that captive supplies do not influence prices".

The cattlemen are asking for a court injunction to prevent meatpacking companies owning cattle.