The owner said there were some drag marks in the grass where it looked as if the animal had been dragged through the gate and loaded into a vehicle.
She thought it would have taken four people to lift the carcass.
The owner said the cow would have been worth around $1000 and was very good meat.
She said it had been recently drenched so wasn't currently fit for human consumption.
Further north, police confirmed a second cow, around five years old, had been killed in Waipoua River Rd sometime between 10pm on September 13 and 6am the next day.
A Facebook post contained graphic pictures of the slaughtered cow with its legs hacked off and the body left in a paddock.
The post said the cow was pregnant and due to calve anytime and "the calf inside her was killed viciously as well".