A new high-tech paint, laced with thousands of micro-dots, is being trialled in the fight against sheep rustlers.
The anti-theft product allows farmers to mark their animals with a forensic code and trace them back to the home farm, if stolen.
The British product - Tectracer - is being considered by New Zealand farmers.
"If the animals are taken from the home farm, we've now got a way of identifying them back to that home farm and that creates a really strong deterrent against stealing the animals," says Tectracer Founder John Minary.
Sheep and cattle thefts are a big problem here, costing $150 million a year.
Timaru farmer Miles Anderson has been hit three times.
"About every five years, this area seems to be hit by rustling and you tend to lose mostly prime lambs," he says.
Tectracer works by assigning forensic codes to individual farms and uploaded to a database.
When stock disappears, the codes are given to police, stock auctioneers and meat works, who then monitor marked sheep.
Mr Anderson wants to go a step further and track individual sheep, using GPS.
"If the meat companies and stock yards incorporate this into their systems, then it will be of interest, not only to me, but to most farmers," he says.
Until then, this latest anti-theft tracker could be the modern answer to solving a centuries-old problem.