There are a lot of great resources that explain the benefits of fermented foods, but I won't go into detail here. Basically, fermented food contains Lactobacillus, which is a live, beneficial bacteria that aids in digestion, is rich in enzyme activity that helps us absorb more nutrients, and leads to a stronger immune system. For more info on the benefits of fermented foods, check out article "Fermented Foods Bubble With Helpful Benefits."
I couldn't find any definitive proof that fermenting the chicken feed cuts down on overall feed costs, but some sources claimed that chickens will eat about 50% less. With all the other benefits, I figured it was worth a try. Since this is our first time raising broilers, we don't have any data to compare, so it is difficult to say if they are eating less, and if so how much less. Also, most of the information available on fermenting chicken feed is directed at layers, not broilers. Since broilers are generally given access to food 24/7 and spend a good chunk of their waking hours eating, it has really been difficult trying to determine how much food to give them. The benefits of fermented food diminish quickly, so I have been feeding them fresh feed 5-6 times a day. Every day they just get a couple scoopfuls more than the day before.
If we end up with underweight birds at our processing day next week, then we will know that they weren't receiving enough food and will have to make adjustments next time. I have also decided to start feeding the chickens fermented feed only in the morning at night, and then go back to offering them their dry food free-choice throughout the day. First of all, it is too much work to feed them every couple of hours, and secondly, I believe everything is best in moderation, so feeding the chickens solely fermented food may not be the best choice. On the other hand, the choice to reduce fermented feed has nothing to do with observation, because the chickens look fuller and healthier than ever!