APIS<http://www.ifas.ufl.edu/~mts/apishtm/apis.htm> on the web is
truly an amazing chronicle of what has been happening -- and is
happening -- in American Beekeeping.  I was digging around there tonight,
and in the process, I found this piece that seems very relevant to recent
discussions:
 
MORE ON FEEDING PROTEIN Dr. Eric Mussen, in the last issue of
his newsletter, From the UC Apiaries, University of California, made some
remarks on my discussion of the Florida protein feeding study in Bee
Science I reported on in the last issue of APIS.
 
According to Dr. Mussen, California experience suggests that stimulating a
large flush of brood rearing when pollen is in short supply will take a
heavy toll on nurse bees, who must sacrifice their body reserves to rear
new bees. He concludes that lack of varied, nutritious pollens in late
summer and fall is the largest contributing factor to colony loss prior to
spring.
 
Disease, parasites, predators and pesticides simply compound the
problem. When the stresses are severe enough, we lose the bees. A new
product of Fleischman's Yeast, Inc. called Torutein (R) CP Dried Yeast is
being made available, Dr. Mussen says. It appears to be suitable for bee
feed, because it is highly processed (appropriate for human food) and
relatively inexpensive. He suggests using it for about 25% of a pollen
substitute/supplement. The price per pound ranges from $.92 to $1.10
before shipping. For more information, contact Pure Culture Products,
10600 West Higgins Rd., Suite 303, Rosemont, IL 60018, ph 800/443-1067.