You need to do more research on Deccox and Rumensin before you make your decision on feeds containing them, and understand that it's not the amount that kills bucks but rather the feed itself (if you're feeding the right feed and hay, you can feed it all day).
Adding ACV isn't doing any good. If it makes you FEEL better, don't worry, it's not doing any HARM either.
Non medicated goat feeds are pretty much ONLY made for milkers. IE does. They will kill bucks, because they won't contain AC.
Lastly, if you were MIXING sweet feed, BOSS, alfalfa pellets, calf manna IN with the Dumor...he maybe ate 1/4 of the AC he was supposed to. Don't rely on minerals, and don't discount the harm grass hay will do to your ratios. Seriously, you need to go read those pages...before you have a dead buck.
And an aside - find a wether companion for the buck, and a doe companion for the doe. You're going to need to separate them eventually.
If you have any questions, feel free to PM me. Good luck.