
Might be a good thing to read up on exactly what vits your dogs need, if you are feeding a raw diet then usually no extra calcium is necessary in fact adding it could cause problems.
I'm not sure from your post if your homemade food is raw or cooked, so if it isn't raw then disregard this. If it is a raw diet, then you could add vit e, vit c, brewers yeast, flax seed oil, kelp. You need to get the right amounts, and worth investing in a Ian Billinghurst book on raw feeding.