An Otipua farmer has increased his reward offer from $1000 to $5000 for information about the slaughter of his prized pregnant cow.

Tom Crowe found the simmental cow, named Jewel, dead and partly butchered when he checked his herd on the afternoon of June 12.

The increased reward came after a North Island farming couple, who have also been the victims of rustling, offered to contribute to its funding when they learned of the slaughter of Mr Crowe's cow.

He hoped the boosted reward would provide an incentive for someone to come forward with information.

"I'm hoping it will scare these guys off or catch them. If it stops it, or stops individuals going through what I've gone through, then it's worth it," Mr Crowe said.

One of his biggest concerns was surprising rustlers while he was on his farm at night spotlight-hunting pests. If they had firearms there could be a dangerous confrontation.

Since the cow was slaughtered, other farmers have told him of stock going missing on their farms, leading him to believe rustling could be more widespread.

He said the brutal nature of the cow's death hit home for farmers he had talked to after graphic images of the slaughtered cow were published in a national farming newspaper.

The cow, due to calve twins at the end of next month, had been shot and her throat cut . The back straps were cut out and all the steaks taken.

The reward is being offered for information leading to the conviction of the culprits.

He said the 12-year-old cow had been his pride and joy. It would have taken at least two people to carry the meat. He believed they had parked a vehicle under a nearby bridge and walked into the field.

Mr Crowe said it was a cold, windy night and shots would not have been heard. The thought of someone on his land with firearms was unnerving.

Anyone with information should contact Timaru police.

- © Fairfax NZ News