Police are warning farmers in the Ashburton area in Canterbury to be vigilant after 36 cows were stolen from a farm.
Senior Constable Mike Seque says the farm's manager is worried sick over the theft of the cows, which are worth $70,000.
Mr Seque says the disappearance follows several thefts in the area, including of two tractors.
The police are checking local meatworks, and nearby farms with increased milk production.
They're asking anyone with information to come forward.