Thieves cut the legs off live sheep in order to sell the meat on the market while leaving the sheep to die from the wounds, according to police reports.
The thieves cut the legs off at least ten sheep, according to police.
The hind legs of the animals, included several pregnant sheep and rare breeds, were cut at the hip and the sheep were left to die.
Farmer William Perkins, who discovered the carcasses in his fields, said the assailants were inhumane to butcher the sheep while they were still alive.
He said that the limbs were removed with great skill and thought to have been sold for meat. The thieves only targeted animals under two years old, as older sheep are classified as lamb.
Police have warned farmers near Stockport, to be vigilant against similar attacks. Perkins, 65, who runs Lion Farm House in the Cheadle Hulme area, has been devastated by the four night attack.
He believes that the attackers used a dog to bring out his flock before butchering the animals. The farm is far from the fields and Perkins and his wife Joan have used their CCTV to try to catch the criminals in the act.
Perkins said: "They were horrible and barbaric, but very surgical. They knew how to cut the legs and they have cut ten sheep at the hip bone. Someone has cut them in the field while it was extremely dark and also knew that sheep were no more than two years old. Every night, I wake up and take a look at our CCTV to see if anyone is there. People who have done this, are inhuman to cut the legs off an animal while it is still alive.
To see what happened the next day was a huge shock," Perkins, who lives with Joan and his son David, and has been raising sheep for 20 years and now has about 70 left, said.
Among the rare breeds that he lost are moorits Castlemilk, black Portlands, Welsh mountain sheep and Hebrideans.
Between two and three sheep were killed in each attack on October 25, October 28, November 4 and November 10.
Inspector Stephen Gilbertson of the Greater Manchester Police, said farmers should consider keeping their animals inside at night.