How much did you use for your horses? Do you use conventional wormers as well?I used DE on my horses, it made their hooves hard and strong. I didn't notice any reduction in flies and did not run fecals to check for worms. They looked slick and healthy to me. I used DE because it is safe for dung beetles. It can't be mixed with water, as it settles to the bottom. I sprinkled it over their feed. For a goat, I would think a tablespoon or two.
@sadieml DE is not good to breathe, whether food grade or swimming pool grade. The swimming pool grade has been heated, which makes it like glass shards, hence the "do not ingest" warning about swimming pool DE. The food grade DE carries a warning not to inhale. I dusted the portable building I used for a feed shed, around the edges for roaches. It worked, but when I swept out the building, I used a paper face mask.
Recently, the feed store offered us 500 pounds of weevil infested crimped corn, which we gladly took. We mixed DE in it and put it in a big trash can outside, well away from our feed shed. The pigs eat it. Do they also get the benefit from the DE and thus no worms? I don't know. We also give the pigs acorns and pecans we raked up, so they get the benefit of the tannins from them. Worms? They certainly look healthy to me. I haven't collected poop and taken to the vet, so I can't give you an absolute either way. But I know they are gaining weight, growing and will soon go to slaughter.
I use Ivermectin in the early spring, before dung beetle activity and in the fall, after dung beetle activity ceases.How much did you use for your horses? Do you use conventional wormers as well?