I see Kurt's point that milk proteins can be altered by fermentation, and
Illya's point that they are broken down into less comlex amino acid groups
during this process, so I retract that statement I made about the proteins
being left "nicely intact."  So "intact but partially digested" might be a
better description of the protein in fermented milk.  However, I don't know
whether or not this partial digestion would make a difference where the
'foreign proteins' theory is concerned.  It seems that it would, in that
smaller groups of amino acids must be more generic (or less bovine), but to
what degree?  Isn't the milk protein casein still present in yougurt and
cheese?  The word casein is derived from the Latin caseus, meaning cheese.

B. Lischer