What breed? Experienced ewes? Any first-timers in the flock they will be rejoining, any hoggs? Good natural shelter for them outside?
I don’t disagree with what others have said, but some breeds, and some mothers, can be very iffy about the plastic macs, and they would be unnecessary on many breeds by 3 days old, especially if there is adequate natural shelter - rushes, trees, hedgerows, walls, etc.
Young sheep, especially hoggs, can be complete idiots around lambs for the first time. I had an innocent pregnant ewe killed in a fracas caused by some giddy hoggs meeting lambs for the first time

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And whereabouts are you? There’s poor weather, and then there’s Cumbria and north of it...
