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.
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