If you are sprouting grains, you are already fermenting them to some degree...the seed goes through the same process and the same enzymes are involved, but it is allowed to sprout afterwards. In fermenting grains for feeding, the whole mass of feed~be it processed feed formulas, whole grains, feed supplements such as bone meal, kelp, etc.~is placed into a bucket, water is added and it is stirred on occasion to aerate it. It can either pull yeast spores from the air or you can charge it to speed up the process.
Most jump start it with mother vinegar to get some well established enzymes into the batch quickly but you can use other forms of yeast cultures. I use the ACV because it's cheap and I have it on hand anyway. Some use kefir, bakers yeast, etc.
After your batch is inoculated and the enzymes are converting your grain proteins into something that is more able to be utilized by a monogastric animal, you can just use part of the fluid or fermented feed as a continuous starter, much like keeping a sourdough starter going, so that you have strong enzymatic presence in each batch of feed that is fermenting. This is called backslopping and the studies showed it to be more efficacious in producing the needed fermentation more quickly and with stronger action.
Here are some links to studies done...there may be more out there since I started fermenting last spring but I've not felt the need to glean more information since starting the process. The proof of its benefits show in the flocks, in the total feed consumed and in the coop environment. The more they can utilize their grains, the less is evident in their waste material, leaving their feces with less smell of the partially processed grains. My dog used to scoop up any chicken poop he came across and I assume it was for the protein derived from the undigested grains, but he no longer finds their feces edible or attractive. To me that means that less of my money is laying on the ground in the yard and in the coop and more is being utilized by the bird.
http://www.ajol.info/index.php/ajb/article/viewFile/60378/48610
http://www.pjbs.org/ijps/fin640.pdf
http://www.ncbi.nlm.nih.gov/pubmed/19373724
To loosely summarize the studies done, the fermented feeds are a valuable probiotic source for the birds, increase the length and absorption of the intestinal villi, can increase the total protein absorption by 12% and thus less feed consumption overall is noted to get the same amounts of nutrient benefits. When used in laying flocks the egg weight increased, when used with broilers less chicks died of dehydration in transport and more chicks were able to show improved digestion when fed the wet feeds early on. The probiotics in the FF were able to reduce the incidents of cocci, salmonella, e.coli, etc. in the flocks and overall health was improved.
Here's a link to the BYC forum thread that another fellow and I had started when I first experimented with this method of feeding with some Cornish Cross meat birds:
http://www.backyardchickens.com/t/644300/fermenting-feed-for-meat-birds
Any questions you may have about the various styles of using this feed, the feeders utilized to do so, the results people have had, etc., can all be asked right there on that thread...it sort of morphed into something along the way and there are a large number of people now using the FF for their flocks of all kinds and even for their pets.
I still use the two bucket system I devised in the beginning but I don't lift the inner bucket for draining off any longer as my flock is much smaller, but it came in real handy when draining off the amounts of feed required each day for the 54 CX birds. The bottom bucket is a good reservoir for keeping my starter intact and for feeding it from above, while still utilizing it throughout the bucket when fresh water is added from above.
In my own experiment with FF I found that meaty chicks arrive from the hatcheries with residual effects of the antibiotics fed to their parents and will have loose, foul smelling feces throughout their short life if their bowels are not recultured. This constant and frequent squirting of their nutrients out the backside gives them a voracious thirst as they are constantly being dehydrated by the diarrhea. Just drinking more water doesn't replenish these valuable electrolytes lost, so many people experience death with CX when the birds are the slightest bit stressed by heat, exercise, or fast weight gains.
The FF changed that outlook for my meaty chicks within a day or so of arrival...normal, formed and scentless little mutes were being expelled instead of the moist, putrid feces that are trademark for this breed. Their water consumption went down, their total feed consumption was considerably less and they were more active in every way. No losses due to health issues, good growth pattern, increased foraging abilities and a coop that had no smell or flies for the 3 mo. they were depositing feces there in the deep litter...this was during the hottest and most humid temps we had had in a very long time and many days 98* weather and 50-60% humidity. My CX foraged all over 3 acres throughout the heat wave and only showed minimal effects of the heat, such as not running as quickly or taking a little break during the hottest times for a rest in the shade.
In using it for layers I've found that it increases the rate and quality of feather regrowth after molting, increases body condition on the same protein percentages I used to feed as dry, increased egg yolk size no matter how small the actual egg itself, and increased vitality in older birds. Others found an almost immediate increase in rate of lay for their younger flocks and increased coloring/barring in their show stock's feathering.
I really can't say too much about how pleased I am with the FF and I won't ever be going back to dry feeds. That's saying a lot after feeding dry feeds to chickens for 35 years. It doesn't take much time, it's not too messy, it cuts down on my feed bill...it's a winner with me. My flock doesn't need sprouted grains because they are free ranged at all times, so the fermented feed grains gives me the probiotics and increase in total nutrient use without all the fussing and fiddling with sprouting grains. Just 2 buckets and a scoop are all that's required and some folks just use one bucket for the same purpose. It's cheap, it's easy and it has powerful results.
Here's a pic of an egg size increase in the same flock, before and after feeding FF.
And here's a pic of a free ranged and FF fed chicken's small egg next to large Grade A commercially produced eggs:
Here's a few pics of the FF in the bucket:
And an example of quick molt recovery for this older hen, accomplished in 7 week's time after starting the FF: