That last month, I feed a higher quality alfalfa hay, which is relatively nutrient dense, high in protein and high in calcium. I'll feed them about 4 lbs of this per day. In addition, I will feed them 1 1/2 lb of grain (currently we are feeding rice, but have used corn in the past). This seems to work pretty well for us. It's more the protein that will make the lambs too big than the energy. If you don't feed enough protein, they won't make enough milk, but if you feed too much, the lambs can get too big. Alfalfa with corn or another plain grain seems to balance pretty well.