Have any of you LI people noticed the new Calcium Fortified 100% milk?

I have two questions:

1.  Does the calcuim that is added to milk like this go away after the
milk has been opened for a while?  I am asking because I know Vitamin C
and other additives evaporate from juice after it has been openned for a
long time or sits out all day.

2.  I have noticed that the Lactaid stays fresh for a long time but when
it goes bad it is nasty.  Does any one think that the added Calcium will
change the speed in which the milk will go bad?  And what about the
consistancy of the milk,  its thicker.  Does any one know why?

Thanks

Sarah