Fermenting chicken feed is a lactic acid process, similar to making sauerkraut. It would be similar to kombucha is a way, though I think k relies more on an acetic acid rather than lactic acid process (I think but don't quote me).
Basic process--take feed, cover with water (non chlorinated), stir daily and in three days you have a lovely probiotic mush that enhances the digestability and absorption of nutrients. It is promoted especially for whole grain feeds like NCO or S&P because the wet mash helps make sure that the chooks get the entire feed, which is a combo of whole grains and more of a powder containing the vitamin additives. If not fed wet, the birds can pick thru and only eat the grains they like, losing much of the powder and some don't eat the legume additions which provide needed protein.
I do feed fermented feed to my bunch (many posts will list as FF). I use an organic crumble or pellet feed as I can't justify the cost of NCO or S&P, though I would dearly love a whole grain mix. I love it, and highly recommend. Do a little research on FF, and there is a great (but very long) thread on the subject for most of the pros and cons, plus you can ask further questions specifically about fermenting there.
