There's also a bit of a terminology thing going on here. To me, a cast ewe is one of any age that is not suitable for breeding, although likely to be older. A sheep which is needing softer going than my hill to breed again is a draft ewe, these would be sold privately or through the ring at a breeding sale and are highly sought after, the price that is paid for them, they aren't going to be killed but are going to have another one, two or more crops of lambs. Then in between are the broken mouthed ewes - correct of the udders and fit, but missing teeth, so worth taking a chance on for breeding is you've got the right type of set up for feeding them.