Fermented feed can only get more fermented...but you need to feed the bugs or they die and new, bad bugs move in~thus the reporting of a rotten smell in the feed. Fresh feed in the mix can feed them well.
If my coop is cool enough for chickens, it's cool enough for their feed....and that bucket gets completely emptied of feed every other day, so it's not hanging around long. (pun intended!

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I keep the lid cracked on my bucket to allow the built up gases from the fermentation a chance to escape..you don't want to have that explode in your face when you open it.
I just leave the buckets sitting right by the coop door. When it's feeding time, I take fresh water and feed(if it's refill day) to the coop and lift the top bucket out of the bottom bucket a little ways and let the excess water drain while I am tending to the water bucket. It is fully drained by the time I refill my water buckets. Then I feed out of it, replace it to the bottom bucket, refill with fresh feed and water, stir well, place the lid with one side not sealed and go about my merry way.
I left this trough feeder open, without a wire overlay, because the meaties would be gone soon. For layer flocks, I'd definitely place wire over the top of the feeder to keep them out of it. With meaties, they'd get on top of it anyway and bear that wire down and ruin it. They are not quite the normal bird and their feed is gone so fast that it doesn't matter how much they get in it...it's gone. And whatever they scraped out onto the floor is soon gone..with CX, there is no nice, quiet feeding times where the hens politely stick their heads into the feeder and eat a handful of bites and go about their way.