Part of the sheep industry in the uplands of the north of England involves the sale of 'draft ewes'. These are ewes who've produced between 2 and 5 crops on the hill, and are sold while still fit to work but would appreciate the easier going further down the hill. Many lowland farmers buy most of their breeding sheep this way, being thereby assured of good mothers, especially if they've had more than 2 crops, as no farmer would have kept a poor performer on to a 3rd, 4th and 5th crop.
Some of these ewes would have been bred as lambs, but the majority of the hill ewes would not have lambed until they were 2 years old. Therefore a 4-crop draft ewe would be 5 years old, and, provided sound of udder and mouth of course, could be reasonably expected to produce and rear another two or three crops at least on easier going.