Sprouting grains is great for chickens and they love it! In the winter you can sprout them indoors (you can use fodder racks or mason jars--you have a pretty big flock, so the racks will probably work best.)
In the non-winter times, you can make them fodder frames (easy with some 1x2s and some hardware cloth). You don't even need to make them this big, but you can! I thought this was a nice picture and the website (where I got this picture) has plans for it here.
I've used a lot of different seeds for fodder: oats, barley, wheat berries, mung beans, lentils, alfalfa, clover, rye, etc. Tractor Supply sells whole oat grains in 50lb bags. It works better with the grazing box, for sure, since the chickens (or other livestock if you have any,) will just eat all the seeds before the get a chance to sprout (obviously.)
I ferment grains. 1/2 Kalmbach's Henhouse Reserve (get from Chewy) to 1/4 hard red winter wheat and 1/4 whole oats (get from our local feed mill in 50# bags), a tblsp each of chia seeds and fennel. I learned the basics from the link @N F C posted above, but I needed a way smaller scale, so use 3 different quart jars and changed it up a little bit. I didn't like fermenting their regular crumbles as that is just mush. I'll make them a mash for a treat by just spraying water over a dish of crumbles rather than ferment that.
Fermenting:
Day 1: I fill one jar half full of the grain mix, then add non-chlorinated water almost to the top. I stir that and cover it with a screened lid I bought on Amazon, but used to rubberband cheesecloth around the top. It has to breathe but keep out gnats or flies. Set out of the sun. I mark my jars with the day of the month I prepared them with a perm magic marker. That scrubs off with a scrunchy.
Day 2: I fill the 2nd jar same as above. Stir the 1st jar, and add water to cover it so it won't mold.
Day 3: I fill the 3rd jar same as above, Stir the 1st and 2nd jar. Make sure there is always a layer of water on the top of the ferment.
Day 4: I drain the 1st jar and serve in silicone loaf pans. (They usually can't tip those over.)
This serves 15 or so chickens. It is not to fill them up, just to give them all a decent serving of prebiotics, probiotics, vitamins and minerals.
Sprouts:
I also sprout the hard red winter wheat in trays I bought on Amazon but you can use any trays. I just didn't have anything so we bought a whole set. I grow it in the house until it's about an inch high. I want those racks like @Jener8or posted above. It's on hubby's to do list.