> ... why the latter insists the three ingredients [brewer's yeast,
> expeller soy, skimmed milk] while the former, only two [minus skimmed
> milk]; in fact, some members on this list would insists on using just
> one [yeast].

There is some confusion about whether the lactic acid in skim milk is
toxic to bees or not.  Choice of soy is also important, since an error
in selection can result in damage.  Stan Sandler discussed this in the
archives some time back.  He has cows, so milk was a natural.  Maybe he
will contribute something here.

Our feeling has been that our bees are confined and we don't want to
take the chance on including milk.  We also don't have milk powder
handy, and besides, it is costly.  Our goal is to get good results using
commonly available, inexpensive products.  We also are looking at making
a supplement, not a substitute.

You may like to write to Dr. Gordon Wardell at the Tucson lab for an
opinion, since this kind of thing is what he is working on these days.
I'm sure if you ask a clear and simple question, he would be glad to
answer it as best he can.  Please remember, however, that bee nutrition
is a very complex and tecnical topic and there is likely no one correct
answer, nor one that fits all situations.

allen
http://www.honeybeeworld.com/diary/