We have never had any problems with respiratory infections or other illness in our flock either, and I think it is due in large part to how strong our chickens' immune systems are because of what they are fed. Breakfast is the most important meal of the day, for chickens as well as for people, and my girls get this custom mix every morning before they get any treats.
I share my "recipe" with you below, and I know from having shared my Flock Block Substitute recipe previously, that those of you who wish to make Chickens' Soup for your flock may have questions about substitutions. Please know that you can make any substitutions, additions or omissions you like. I used what I have on-hand, cleaning out the freezer and vegetable drawer in the process. The only required ingredient is water. We know that water is critically important to our flocks, so I'm happy.