Authorities in Virginia are investigating the theft of $250 worth of bull semen stolen from a farm in Augusta County.

Lt. Dennis Back of the Augusta County Sheriff’s Office said 10 containers of semen were stolen from a farm in Mount Solon, Va., sometime between Jan. 24 and Jan. 29, the Staunton News Leader reported Wednesday. The bull semen was stolen from a barn, he said. It’s unclear why the bull semen wasn’t reported stolen until now.

Back said the case is highly unusual. “I’ve never seen anything like it before,” he told the paper.

Jean Schofield, an employee of the North American Breeders Inc. semen collection center, said the bull semen could be worthless unless the thieves took precautions to store it. Schofield told the News Leader that bull semen is usually stored in tanks, ampules, straws and goblets.

“They have to be in liquid nitrogen,” she said. “If they didn’t take the tank … it’s absolutely no good if it thaws out.”

Schofield said bull semen is used to develop traits in a herd that you that are not possible get through natural methods. She said bull semen can be worth as much as $400 to $500 per straw.