Well, I add 25# to a 400# batch of grain for about $10 so 
it doesn't take any of my time and $10 doesn't make me or break me.  I have 
a friend who feeds it free choice to her fowl (pheasants, chickens, ducks, etc.) 
and she swears it improves their feathers, shine and sheen and overall general 
health.  I wormed our horses again this fall with liquid 
ivermectin just to be safe and never found any worms...I expected to find 
worms in the fall.  None.  The DE in the grain was the only thing that 
might explain that.  I don't know but it certainly can't hurt 'em.  
Maggie