Devon and Cornwall Police are investigating the theft of 25 pregnant ewes from farmland close to the A30 at Sourton before Christmas.
The animals were stolen sometime between Friday and Monday, December 17 and 20.
The in-lamb mule (crossbreed) ewes are all marked with black paint on one of their back legs.
Anyone with information regarding this incident is asked to email [email protected] or call 101 quoting crime reference number CR/112014/21.
Information can also be passed anonymously to the independent charity Crimestoppers by calling 0800 555 111 or reporting online at www.crimestoppers-uk.org