Great information! One question please? What about using powdered buttermilk to bump up a commercial feed like Nutrena?
I don't see why not. The problem with powdered milk is that it won't adhere to feed and remain at the bottom of the feed trough where chickens can't pick it up with their beaks. In that case, you'd have to moisten the feed with water. Fresh buttermilk is affordable enough, so I just use that. I try to give a bit of variety, and sparingly, depending on what's happening with the birds. I use higher quality organic feed rations and supplement water weekly, so I'm not concerned with deficiencies. No salt tuna and low fat buttermilk are two highly digestible animal proteins I use.