While looking for information about fenbendazole and feather damage, I found this about Moxidectin. Looks like it might be a good one to consider as an alternative wormer:
http://www.auspigeonco.com.au/Articles/Moxidectin_product_review.html
Wormers in water... Sigh. Do you know that the ivermectins sold for cattle are *not* water soluble? If you doubt me, just put touch it and you'll see that it feels oily. If you still don't believe me, place some water in a clear glass, add a few ml of ivermectin, stir well, then come back in 30 minutes and you'll see it floating on the top. Or just google the product you're using with the letters MSDS (material data safety sheet). In it it should say if the product is water soluble.
Time for me to do another experiment, lol.
-Kathy