I use 6 pounds of mixed grass hay running 13%ish protein per day will feed a sheep with minimal suppliment of either barley or Corn/protein sup, to 16% (say half a pound ea.) will feed my sheep. Sheep averaging 130 pounds and scoring 3+ or - a bit at the start. You'd need less high quality hay and perhaps no suppliment if your sheep are in good shape, you might need more suppliment if they are not. Mixed hay is a nice base to work from, even untested it will (if harvested in a timely ,manner and as no-rain crop) will give a nice minimum 12%-14% ration. I figure if I have 2 round bales (650 pounds) per sheep and 1000-1500 small squares I have plenty to feed 200 ewes and 100 lambs (diminishing to zero by Christmas) for 210 days through lambing in April/May. New England is only 180 days? Yes I have hay left over but feeding through midMay is not unheard of here either.