Are you SURE you're not getting any brain or spinal cord matter? Boy, I wish I could unread a few books about prion disease. But it's a real consideration in this day and age. I have a relative who is a government veterinarian and he would have my head if I ate brains or used bone meal in my garden. And he's an old fashioned conservative who thinks spending extra for organic veggies is silly - not exactly an alarmist.
How well do we process bones, anyway? I have no idea if this is an efficient way to get calcium or not. Nutritionist folks?