Published online by Cambridge University Press: 06 May 2016
Many thousands of cast-for-age Blackface ewes in Scotland and England are transferred each year to lower ground after producing four or five lamb crops on their native hill farms. It is then customary to use on them rams of another breed, often the Border Leicester, with a view to the production of more profitable lambs than can be obtained from pure-breeding (Bywater, 1945). Such is the scale on which this procedure is practised that it becomes an important consideration in any breeding plan for hill sheep that the cast ewes should be adapted to this phase of their careers as well as to that which precedes it on the hills. The outcome of selection work with Blackface sheep consequently cannot be fully assessed until the cast ewes have reared crossbred lambs, and have been finally disposed of.