Never seen that one. When was she due? If lamb failed in utero it may have been reabsorbed. Lots of ewes are dry or drying up after 3 or 4 weeks this year. They need body fat to produce milk and if they haven't got it the lambs will die but the ewe will survive to breed the next year - Mother Nature being efficient, I guess. If this is the case it won't matter how much high energy feed she has - it will help her survive but not to produce milk.