Jack said:
"I don't think there is any reason that cow's milk, straight and simple
cannot be given by six months of age, as long as it is not the baby's only
food.  And if the baby is getting iron containing foods, he *may* lose more
blood from the gut, and maybe the stores will be a little lower, but he will
not become anemic. "

The problem I see is excess cow's milk consumption. I'm often telling
parents to limit the cow's milk. I tend to think parents who switch from
formula to cow's milk at 6 months are going to end up feeding that baby 35+
onces a day.
-Rob