Authorities in far southern Minnesota are investigating the theft of $70,000 worth of bull semen.

The theft happened on a dairy farm in Leroy, Minn., near the state's border with Iowa, sometime during the first week of April.

Mower County Sheriff Terese Amazi said a farmer called the police, saying a storage canister with vials of bull semen had been taken from his unlocked barn.

"I can't recall ever having had a report like this," Amazi said. "It was one canister containing many, many vials."

Amazi said the farmer was only away from the farm for a few hours on Easter Sunday. Each vial of semen can range in cost from $300 to $1,600 apiece.