In Australia it is very common occurance to see bees feeding on cracked grain, meal or the like.  It is normally during a period of pollen dearth.  I have had bees on a friend's place and the bees were working the feed in his chicken pen.
 
We have had trouble with bees going to the cattle feed in lot feeders where cattle are fattened.  In one case, hives have had to be shifted because the bees were stopping the cattle from feeding.  There is a soulution.  Add molasses to the dry feed and it will stop the bees from feeding.  Not sure why but it works.
 
In dairy farming areas, bees will feed at the milking bales where the cattle are feed meal, pollard or cracked grain.  I have a cousin who suffers from this problem at his dairy (not my bees).  When the natural pollen supply again comes back on line, the bees stop pinching from the dairy.
 
After all we feed bees torula yeast, brewers yeast, corn dust, linseed meal and the like so why shouldn't they go for the dust in things like chicken and cattle feed.
 
 
 
Trevor Weatherhead
AUSTRALIA