Re: How is calcium produced in dairy milk?

Calcium is a mineral that is vital to many aspects of life.  Calcium is 
sequestered in the skeletons of vertebrates and in the shells of 
invertebrates.  Calcium ions are used in cell signalling and are involved 
in the passage of materials in and out of cells.  So in mammals calcium is 
not just produced in milk, and calcium along with lots of other materials 
contribute to the total nutrition.

Some foods do contain more calcium than others, but adult mammals have a 
considerable stock of calcium.  A diet terribly deficient in calcium would 
be deficient in lots of other dietary needs as well.  Severe nutritional 
deficiences can affect reproduction.  Females may not ovulate, and there 
fore cannot become pregnant.  Remember, mammals produce milk in response 
to hormonal changes associated with giving birth.  So a more likely result 
of poor nutrition is no milk production at all.  If a female is in good 
enough health to produce a viable offspring, then their milk will contain 
adequate calcium.