One can use soy milk or rice milk in place of cow's milk.
Cow's milk because it is a mucus creating food item and because of its heavy
and thick casein protein - may not be suitable for human use.    Humans may
have digestive problem with the casein protein contained within cow's milk.
See these web sites:    www.notmilk.com   and  www.panix.com/~nomilk  .

There's nothing really in milk you can't easily get someplace else.
Soymilk by comparison is going to be low in calcium, unless fortified.
It also doesn't have as much magnesium or potassium as milk. The last
two are easily obtainable in fruit juice. Calcium fortified OJ makes
soy milk look bad, mineral-wise, and also has folate.  Depends on what
you're looking for.

SBH

Read this before you consume any soy product:

http://www.westonaprice.org/soy/soy_studies.html

TC