Some of the manufacturers use a mineral oil base, others use an alcohol, and or water base. The actual active ingredient, ivermectin is the same in ALL the brands as labeled. They are in fact apples and apples, EXCEPT when you are talking about name brand Ivermectin Plus, thats has an added active wormer for liver flukes, and also the time that you put them on, most alcohol and water based brands are very weather sensitive, meaning that any moisture will dilute or wash the material off.
We use the knock offs all the time. Jeffer's is selling it for less then $80.00 per 5 liter jug now! it has suited us just fine.
You may be getting some resistant parasites, that in fact would be no better treated then if you used a name brand of ivermectin.
Where did I get my information?
From a class that the NC State University put on for us this summer regarding parasite control.................it's getting harder and harder to get good control no matter what you use these days. They are finding that goats are the 'indicator' livestock to watch for resistance. Fecal counts are a must when trying to get good control. Use the same wormer until they don't work anymore, then switch. BUT not before, is what they are telling us. :cboy: