The experiment involves turning 4-year old sow pigs into rashers. Bacon has historically always been made from young male, or boar, pigs. Sows, whose sole purpose is to breed, have been considered tough and inedible in Britain and their meat is sold to German bratwurst makers and Italian salami makers. Long-standing butchers said the only time sow meat, which tends to be very fatty and dark in colour, has been sold as a cut of meat was during rationing in the Second World War.