 An important event not only in the history of domestic sheep , but of all livestock , was the work of Robert Bakewell in the 18th century . Before his time , breeding for desirable traits was often based on chance , with no scientific process for selection of breeding stock . Bakewell established the principles of selective breeding — especially line breeding — in his work with sheep , horses and cattle ; his work later influenced Gregor Mendel and Charles Darwin . His most important contribution to sheep was the development of the Leicester <unk> , a quick @-@ maturing breed of blocky conformation that formed the basis for many vital modern breeds . Today , the sheep industry in the UK has diminished significantly , though pedigreed rams can still fetch around 100 @,@ 000 Pounds sterling at auction . 
