CindyinSD
All will be well, and that will be well is well.
It doesn't have to be covered with water to ferment. Many ferments are wet, but much of the time this is a factor of the type of fermentation. For example, when fermenting pickles it's important to keep the veggies covered in water to prevent the growth of mold organisms. When fermenting bread dough (also a lactofermentation process) this is not a consideration.Everything I've read about it says to keep it covered at least 1in over the grain with water
I mix my feed to the consistency of a wet bread dough and never cover it with water. I ferment for a few hours to overnight. I can tell by the delicious aroma that my feed is fermenting; it smells a lot like rising bread (and it will actually rise, so be careful or you'll have a mess). It can warm up as well.
Fermenting for long periods of time in the absence of oxygen, in a fairly neutral pH, without sufficient salt can risk growth of organisms you do not want.
I do not put my fermented food in metal containers. It is acidic and can corrode the metals. Plastics are fine. Those rubber containers are fine, too.
I don't ferment feed much in the winter. A lot of days here, it is cold enough to freeze the feed before the birds can eat it, so I give them dry feed.