Police are continuing to investigate 500 cows believed to be stolen from an Ashburton farm.
Ashburton Police visited the property and took statements from people there.
Senior Sergeant Scott Banfield reminded farmers to ensure they took measures to help prevent stock thefts.
"All farmers should be checking their boundaries and fence lines on a regular basis.
"It's unlikely the theft of hundreds of animals could be completed at once, and is more likely that multiple thefts could be carried out over a period of time.
"Regardless of the size of your property, ideally stock numbers should be checked once a week.
"Farmers should also be keeping an eye out for unexpected signs of herding near their boundary lines too."
It was essential the community worked together to keep police informed.
"Neighbours should make a note of any movement of stock, particularly if it's at an unusual time of the year.
"If possible, make a note of any suspicious vehicle's registration number, and a description and direction of the vehicle and what it was carrying.
"Even a photo on a cell phone provides a significant amount of information to Police."
Banfield said farmers should also be reviewing their auditing systems:
"There are almost always improvements which can be made to the management and security of stock.
"Clearly tag animals and keep accurate stock numbers.
"Enhanced security and signage can help to deter opportunistic thefts.
"Items such as animal tags and equipment should be kept in a secure facility."
The theft of 500 cows from the farm will cut milk production by up to 200,000kg.
Waioto Farm administrator Pennie Saunders posted on Facebook to try and track down the missing herd.
"We have had approximately 500 cows stolen from our large dairy farm in the Ashburton area."
Saunders said the "phenomenal" theft was first noticed in late August but could have taken place earlier.
"It's significant, it's huge, there's no joking about it. We're now focused on coming up with a farm management plan on how to manage it, to be able to cope."
Saunders said the loss of production meant the farming system needed to change for the season.
She said the thief could have stolen the cows a "unit load at a time".
"To see a large number of animals loaded out isn't unusual [in the area]."
Federated Farmers Mid-Canterbury president Michael Salvesen said cows have gone missing before around the area but in "relatively small numbers".
But only up to 30 cows were taken.
This situation was "unheard of".
He said this was "pretty organised" and the theft would have moved the stock with a truck or walked them.
"It would happen over a period of time."
He said they would have taken up to seven cows from each group "over a matter of time so people didn't notice it was disappearing".
Canterbury Police received a report on August 25 about the theft.They are making inquiries.
If anyone has information which may be of use please contact Canterbury Police on 03 363 7400 and quote file number 160825/7150 or Crimestoppers on 0800 555 111.