CHS Inc., the nation's biggest farmer-owned cooperative, said Wednesday that its fiscal third-quarter profit jumped 51 percent after a one-time boost tied to the spinoff of its flour milling operations.

The Inver Grove Heights-based co-op's ag-related operations also experienced a big jump in profit that offset a modest decline in its energy-related businesses.

For the three months ended May 31, CHS earned $379.5 million, up from $250.8 million in the same period a year ago. Revenue was $12 billion, flat with a year ago.

The co-op experienced a one-time gain of $108.9 million for its flour milling ­business, which was spun off into a new firm called Ardent Mills that also includes the flour milling operations of Cargill Inc. and ConAgra Foods Inc.

CHS said it saw stronger performances from its retail agronomy, wholesale crop nutrients and grain marketing businesses.

The co-op's energy business, which includes Cenex retail gasoline chain, saw its operating profit decline to $205.8 million from $220.2 million a year ago. CHS said it experienced lower margins in its refining operations but saw gains in lubricants and transportation.

Meanwhile, the co-op's agriculture businesses had an operating profit of $109.1 million, up from $40 million a year ago. And its corporate-related operating profit was $124.7 million, up from $19 million a year ago.

U.S. antitrust regulators in mid-May provided the final approval of the $4 billion merger that formed Ardent Mills. The merger was announced in March 2013 and underwent a lengthy antitrust review. The new combined firm, based in Denver, is now the nation's largest flour milling venture.

For the first nine months of its fiscal year, CHS earned $881.7 million, up from $869.6 million a year ago. Nine-month revenue was down 3 percent to $32.7 billion due mainly to lower grain prices, CHS said.

Evan Ramstad • 612-673-4241