There are whole topics devoted to this debate. If you read the first 10-50 messages of any of the massive "fermented feed" threads, you'll learn a lot of the debate aspect.
Briefly, I'll tell you WHY I do it, the how is a whole other topic.
#1 Reason: Probiotics (improves digestion and immune strength in any animal, IMO and is my main reason for fermenting feed)
#2 Improved nutrition (enhanced nutrient bioavailability, increased vitamin content, easier digestion because it's wet food)
#3 Chickens love it
#4 Seems to reduce my feed cost slightly
IMO, if you want to do one thing to improve the general health of any animal, give them some probiotics. It will enhance their digestion and immunity and therefore help them better resist some diseases. If chickens are free-ranging, they are getting a good amount of probiotics already from any plant material they eat and perhaps from small animals like mice (I'm not sure if insects' GI tracts contain probiotics, but I imagine so). But if they're cooped up, they aren't getting really any at all. At least for humans, most probiotics do their job on the way through the GI tract and do not "colonize" the GI tract, contrary to popular belief. I have seen how probiotics have improved my own health (better digestion and mood) and have seen at least one soft-shell laying chicken be temporarily improved by increased probiotics (I had to keep up the probiotics at a high enough level to keep her shells firmer). And as far as I know, it's rather difficult to overdose on probiotics in food form. You could probably do so if you were taking probiotic pills and say perhaps took a whole bottle of them (would probably just give you gas or diarrhea or constipation), but it would be hard to eat too much probiotic food.
I am not going to try to convince you of the "improved nutrition" aspect. There are TONS of books and web links out there going over the topic. Basically, the more I read about soaking grains, fermenting them, sprouting them, etc, the more and more I am inspired to base more of my own diet upon them. It just makes sense to me to do it for the chickens as well. I don't also sprout any grains (some people do), I just do the FF for now.
As for #4, I haven't been able to calculate well this year, as our flock size has fluctuated a lot in the past 9 months. Last year when I had a more stable sized flock I did calculate out a few months and I think I was saving 10-15% or so in feed costs. Not a huge savings and not the main reason why I do it. I think some folks claim 25% or more feed cost savings. But I think this has more to do with rationing out feed vs. ever having free feeding available (feed always available whenever they want it). You could ration out dry feed and notice a huge cost savings difference, because the chickens are less likely to waste feed.
Unlike some who feed a diet of 100% fermented feed (with or without free ranging), I choose to feed about 10-20% of their daily intake of formulated chicken feed (with free ranging in spring-fall) as fermented feed. The remainder of their chicken feed is just plain dry feed. The main reason for this is I don't think it's normal to feed any animal a diet of 100% fermented foods. I know some people do it and swear by it, but it's never made sense to me. It's also a lot of work to ferment feed (the way I do it) for 50+ chickens if their only feed source is FF.
There is some work involved, especially the way I do it. I make batches at a time vs. a continuous fermenting process. Everyone out there will have their way, their reason, for why their method is best or better. IMO, the "best" way to ferment your feed is to just do it. Do it in a way that works for you, or makes sense for you. Try different methods out and see which one fits you well, or makes the most sense to you. Some people will want the least labor intensive method possible and will get "good enough" nutrition from it and others (like me) would rather put a little more effort into the fermenting process and get higher quality nutrition from the feed. It depends on what matters to you most and that will determine what method is "best" for you.
I've not given you any links to follow up on, just my own experience. And since you and I don't know each other, I don't expect you to believe a word I say. But perhaps some of this will inspire you to learn more about probiotics and fermented feed in some way.
But a question for you: Why are you even considering fermenting feed? What do you hope to gain from it?
