Rancher Cliff Bracher awoke today and found nine pregnant cows - about a fourth of his herd - were shot at his Holdman-area property.
Three were already dead, and some others would have to be destroyed.
"They were bred cows and were going to calve this week," Bracher said.
"I think people just drove along the county road and shot them. They probably didn't know who they belonged to, and didn't care," Bracher added.
He and his family were able to save some of the calves by delivering them by Caesarean section this morning.
The monetary value of the pregnant cows was probably about $900 each, but the offspring could have grown and increased greatly in value, Bracher said.
"It's a disappointment. It's a setback in the business," he added. "It's a saddening thing. They're girls that we brought up from babies and put back in the herd."
Bracher will donate any meat from the cows to the Agape House in Hermiston.
"I'm going to try and salvage what I can," Bracher said. He called a mobile slaughter to the farm to help.
No information about the incident was present on Umatilla County Sheriff's logs, though Bracher said he called there.
He said he would try and preserve evidence, such as tire tracks and any bullets recovered from the butchered cows.
"We took a lot of pictures," Bracher added.