ST. LOUIS — The Obama administration today proposed new antitrust rules for meat companies that reflect a willingness by the USDA to shift the balance of power between farmers and processors and to regulate an industry long-dominated by a handful of corporate giants.

The rules would place the sharpest limits on meat companies since the Great Depression, drastically lowering the bar that farmers and ranchers must meet to sue companies whom they accuse of demanding unfairly low prices.

The rules would dictate how meatpackers buy cattle on the open market and prohibit them from showing preference to big feedlots rather than buying from small producers.

They also would limit the control chicken companies have over the farmers who raise birds for them. The companies couldn't require farmers to take on debt to invest in chicken houses, for example, unless farmers were guaranteed to recoup 80 percent of the cost.

The law also would make it easier to file suits under the Depression-era Packers and Stockyards Act by stating that farmers don't need to prove industrywide anticompetitive behavior to file a lawsuit under the act.

Secretary of Agriculture Tom Vilsack said increasing consolidation has strengthened the bargaining power that big companies have over farmers, giving producers an ever-decreasing share of the money consumers spend at the grocery store.

As a result, farms are failing, with the number of hog farms dropping from 660,000 in 1980 to 71,000 now. The number of cattle farms has fallen from 1.6 million in 1980 to 950,000.