PORTLAND, Ore. (AP) _ A 600-pound sow on her way to slaughter tumbled from the back of a truck and tied up traffic for more than two hours before she was scooped up by a front-loader bulldozer, police said.

Traffic on Interstate 84 moved at a crawl Monday as morning commuters inched past the hog known as ''Mama'' and television crews who recorded the painfully roundup efforts of highway workers, police and Mama's owner.

''I heard the tailgate fall off, and I looked back and saw her standing in the road,'' owner Fred Mickelson said with a weary sigh. ''I thought: 'Oh no. We've got real trouble now.'''

Mickelson said Mama was ''pretty lively'' when she hit the ground, lumbering between cars and causing general havoc. There were no accidents, however, and the hog quickly made her way back to relative safety in the far right lane.

When efforts to move the hog back into the truck failed, Mickelson pondered the choice of killing her or having a veterinarian tranquilize her. Either way, he lost, because the slaughterhouse would not accept a dead hog and state law requires hog owners to wait a month before selling a hog that has been tranquilized.

The solution came finally when highway workers used a massive front-end loader to pick up the hog and dump her unceremoniously back on the truck.