OMAHA — ConAgra Foods, Inc. will close a cereal and nutrition snack bar plant in Grand Rapids, Mich., by February 2015. The announcement comes less than four years after ConAgra said it would invest approximately $73 million and create more than 200 jobs over the next five years at the plant. ConAgra acquired the facility as part of its acquisition of Elan Nutrition, a privately-held formulator and manufacturer of snack and nutrition bars, from an affiliate of Sun Capital Partners, Inc. in mid-April 2010. ConAgra is expected to scale back production at the plant in the coming months, with most operations ending this summer. Research and development work is expected to continue until early next year.