I also give calcium supplements. In addition, I try to get them to eat 500mg chewable Vitamin C tablets about twice a week. Vitamin C is a powerful antioxidant and can help prevent heart murmurs and heart-related defects in the kits and in the mother. I also give a water bottle of 50/50 water and cranberry juice starting when I first feel movement from the kits, to encourage her to drink more water, which aids in milk production.
I don't give alfalfa hay anymore, as I noticed with my females, it caused constipation and some bloating. So I just give the calf manna in their food, and I give them Tums with Calcium from time to time, and provide cuttlebones at all times.