Goat's milk is deficient in several very important nutrients (folate, I think,
and iron being the two most glaring), plus has the wrong protein blend for a
human infant, and is NOT recommended for use in infants under a year (any more
that is whole cow milk).  As it is a full milk of another species, it is just
as allergenic as cow milk.  If you wouldn't consider giving your child whole
cow milk before a year of age, you shouldn't consider using goat milk, either.

Your best bet for additional calories for your Guatemalan infant is to use
either donor human milk (if you can obtain it), or one of the standard infant
formulas.  The formulas are not poison and actually are reasonably adequate as
a source of additional calories in this instance.  The formulas are closer to
human milk in nutrient composition than is goat milk.  (They do, of course,
still lack some important stuff found in human milk, and don't have the
antibodies/immune properties, but neither whole cow milk nor goat milk
contains appropriate immunity for humans.)

Linda L. Shaw MD FAAP
Pediatrics