Originally Posted by chookchick
I am totally at a loss as to why one would put it in the feed of their animal, chicken or other. In landscaping, I've always been told that the dust is completely inactivated when it gets wet. This would correlate well with the study that Ivan posted, saying that the insects were basically dessicated by the dust. Correct me if I'm wrong, but I believe my chickens have quite a bit of moisture in their digestive tracts!
Let me preface this by saying I am by no means a believer that DE is a useful worm preventative. (I have no evidence that it *isn't* either, but I would describe myself as "agnostic leaning towards skepticism" )
HOWEVER, that said:
Just because something seems theoretically impossible does not mean it does not happen. There are any number of things that have seemed impossible that turned out to be quite true, just b/c people misunderstood the nature of what was happening when making those 'impossible!' pronouncements. So personally, as a former research scientist, I am more swayed by good data than by theory, although theory is of course nice and can be worth considering when there *is* no good data to go on.
One can imagine at least one mechanism by which feed-through DE could decrease worm load. As far as I can recall from invertebrate biology, many internal parasites (not all) are ingested as inactive, well-protected cysts or eggs, from which the critter "sprouts" once the cyst or egg reaches the intestinal tract. In principle, if DE were to damage the cyst or egg wall such that stomach acids could damage/dissolve the critter inside, that would have the effect of discouraging worm infestation.
Does that happen? Who knows.
I really really wish someone would do a good research-based STUDY of it. I had read somewhere that some poultry science type was wantin' to test some of these old-timey things properly; I don't remember any more than that, but it sure would be excellent to have it HAPPEN.