We feed it to our baby calves to prevent coccidiosis. Everyone around here uses it. We only do it when they are in the corral, and when it's the muddy season, because puddle drinking seems to be the culprit that causes it for us. We just put some in the back of the shed in a small tub, and they just love it. It works too.
I also sprinkle it on my potatoes to control Colorado potato beetles. It doesn't work on adults, but when it comes to those little ones that have just hatched, it kills them as well as any chemical ever could. It's the method of choice with organic gardeners for this purpose.
It costs about 26 dollars for a 50 pound bag, and two or three bags will do us for a calving season, with leftovers going to the garden. It more than pays for itself.