Investigators say a malfunctioning electrical motor on a feeding system sparked a fire that killed about 1,700 pigs at a large hog farm in southeastern Utah.

Officials with Circle Four Farms spent the weekend disposing of the pigs' bodies following the Friday evening fire at a barn in Milford.

Authorities responded to a call about 8:30 p.m., after the blaze had collapsed the roof and was dying out.

Spokesman Don Butler with the farm's parent company, Murphy-Brown LLC, says 500 pigs survived the fire. No people were at the barn at the time.

Butler says it appears two safety mechanisms meant to shut down the feeding system if it overheats did not kick in.

Circle Four Farms raises and markets 1.2 million hogs per year and employs about 425 people.

Copyright 2011 The Associated Press.