Rustlers have stolen 600 sheep worth £50,000 from a farm in Lincolnshire.
Thieves forced open a gate to a field on the A18, near Melton Ross, heading away from Barnetby Top, and stole 200 sheep and 400 lambs.
Humberside Police said a large livestock vehicle or trailer must have been used to remove the sheep sometime between 7pm on Tuesday (2 June) and 7.15am on Wednesday (3 June).
Officers have appealed for witnesses to come forward with any information.
PC Tracey Teal, investigating for Humberside Police, said: “It is clear that a large livestock vehicle or livestock-type trailer would be required.
“This type of offence causes considerable upset, inconvenience and disruption to the victims, having a high impact on a business which takes years of time and dedication to build up.
“It is very important that the person or people responsible are located and prosecuted.”
Anyone who saw people or vehicles parked in the area at the time is asked to call Humberside Police on 101 quoting crime reference 2117346.
Alternatively, call Crimestoppers anonymously on 0800 555 111.