WASHINGTON -- Proposed anti-pollution regulations for big livestock and poultry farms could cut production and force operations to move to areas such as the Midwest and Plains where there is plentiful cropland for using manure as fertilizer, a government study finds.

It also shows that the industry restructuring could raise commodity prices and increase farm income by nearly 30 percent, without significantly affecting consumer prices.

Some financially shaky farms "will likely be forced out of business" by the cost of complying with the regulations, the Agriculture Department study said.

The rules were proposed by the Environmental Protection Agency at the end of the Clinton administration. They would expand the number of cattle feedlots and hog farms that have to get pollution permits, and impose new controls on poultry operations.

The rules are intended to cut down on spills and farm runoff that have fouled lakes and streams in a number of states, from North Carolina to Washington.

Every farm and feedlot would have to develop manure management plans that restrict the amount of manure that can be applied to cropland as fertilizer. Farms could spread no more manure on their land than their crops can use.

The rules are under review by the Bush administration and could be revised. Their effect on the livestock and poultry industry will depend largely on how much manure crop farmers are willing to put on their fields, the study said.

Manure is now used as fertilizer on about 17 percent of the nation's corn crop and 9 percent of soybeans.

If manure use can increase to 40 percent of a region's fertilizer needs, there would be little effect on livestock and poultry farms. Production would stay largely the same and there would be little shift from one region to another, according to Agriculture Department economists.

But if manure use does not exceed 20 percent, the effects would be substantial:

Production, as measured by the number of animals, would drop by 29 percent in the Southeast, 26 percent in the Rocky Mountain states and 21 percent in the Appalachian region, which includes North Carolina, the No. 2 state in hog production, the study found.