Detectives are hunting thieves who stole security fencing from Parys Mountain in Amlwch.
It's believed around 40ft of the high metal square mesh fencing - which is around 7ft high - was removed at some point between last Sunday (13th) and Monday (14th October).
PCSO Rhys Evans from the rural crime team at North Wales Police said: "As a result of the fencing being removed, the victim’s cattle were on the road in a poorly lit area, which could have caused a serious road traffic collision."
Anyone with information should contact North Wales Police on 101 or via the live web chat, quoting reference no. Q155146.
New parking system at Newborough Forest
Funding available for community schemes
Welsh Cup: five bailed after pub disorder
Llanerchymedd barn fire 'deliberate'
Welsh gig guide launches app
