I am sure someone already answered, but JIC, I will answer.
All food can be fermented. I ferment dog food for about 3 days the first time, 2 after that. "call of the wild" from TSC takes forever to ferment. For the chickens I ferment cracked corn, and whatever I grab. Mash, crumbles or pellets.
Step 1) Get about a 5 gallon bucket (unless you only have 5-6 chickens)
2) add whatever food you are fermenting. Fill the bucket about half way. The food will expand.
3) Add water (the warmer, the faster it ferments) to above the feed
4) add a glug of Unpasteurized ACV with mother. A glug is 1/4 cup or so. It doesn't need to be exact.
5) stir it up, and after a few hours add more water to keep it wet.
6) The first batch takes about a day (a little less) to ferment if it is at least 60ish where you keep the bucket. Overnight after that.
Stir twice a day, giggle at the bubbles, and you don't have to add more ACV. Just water when you add feed.
7) strain, and serve. It may take twenty minutes to strain. Be sure to not use metal. The vinegar will ruin it.
8) Giggle at the bubbles again.
You can also check out "fermenting feed for meat birds"
Then giggle some more.
A glug.....I am assuming a goood.....triple shot......
BTW if you let it ferment two weeks, what do you have?